Answering the question why the maximum number of phenomena occurs precisely at the perigee and apogee, it is worth resorting to the concept that the retention of one planetary body by another is due to the attraction between their central parts. And this will certainly be the most suitable material for research. Let's consider it reasonable to start with the notion that the phenomena observed on the planet's surface are mainly generated by endogenous forces. Therefore, first of all, the question arises: will the solidified shell of a planetary body behave in the same way if the core changes the mode of action on it?
How can I understand this question more clearly? For convenience and a figurative concept, we will consider a schematic representation of the interaction between two planetary bodies A and B. The shells will be designated C and C1. Kernels - D and D1.
If the planetary body A acts by its gravity on the planetary body B, then first of all this action of mutual attraction arises between the nuclei D and D1. The nucleus D of planet A acts on the nucleus D1 of planet B, pulling it towards itself. The C1 shell around the D1 core will be in a balanced state all the time if planet B rotates around planet A in a strictly circular orbit.
What will happen to the solidified shell if the planetary body B moves around planet A in an elliptical orbit? Should there be any changes in the hardened shell or not?
To come to a definite answer, one should start with the assumption that the shell of an orbiting planetary body does not experience any other weight than its central part. Along the way with this, one should bear in mind the concept that both the inner part and the outer shell have inertia during movement. But whether with the same force, it will become clear later. An important role here is played by the centrifugal force, which all the time accompanies the rotational movement of the planetary body around its center. Let's trace how and for what reason this or that deviation from the norm occurs.
If the forces of attraction between two planetary bodies consist only in the mutual attraction of their central masses, then each body separately solidified shells, the geosphere and the selenosphere, are held by the force of gravity of their centers. During the circular motion of one body around the other, centrifugal forces arise, which, as it were, try to tear off the solidified shell from the center of gravity on one side of the planetary body and bring it closer to the center of gravity on the other. It is logical to conclude here that the satellite's gravitational field is uneven. If the satellite were all the time revolving around the center of gravity in a circular orbit, such an abnormality would be stable and would not cause any deforming changes in the solidified shell. But since the satellite moves in an elliptical orbit, then at the moments of the most distant and most approximate distance to the center of gravity, there is a mismatch in the gravitational relationship between the core and the solidified shell.
The mass of the solidified shell experiences not a uniform circular motion, but, as it were, acceleration and deceleration under the action of its own center of gravity. At perigee, the total mass is accelerated. During movement, every body tries to maintain a straight-line movement. And the greater its speed, the more force it deviates to a rectilinear motion from a circular one. Therefore, it turns out that at perigee, the core, as the force of its own gravity, creates the conditions for the movement of the total mass of the satellite around the planet in a circular orbit, and not along a rectilinear path, to which the mass of the solidified shell tends all the time. It turns out, as it were, two directions of movement: circular and straight lines. Although these two directions are constantly concomitant, the difference between them is most noticeable at perihelion and apogee, when (for a better understanding) the movement is closer to rectilinear it turns into circular under the influence of its own center of gravity - the nucleus. It is, as it were, simply put, loosens the elastic hardened shell from the inside. Therefore, this "shaking" and affects the weakest points in the hardened shell and makes itself felt on the surface. To clarify this circumstance, it should be added that in every planetary body that lives its own life, there is an excess pressure inside it and of a sufficiently high order, this is not counting the gravitational pressure from the outside. For a correct understanding of this truth, no special research is required in unattainable depths. The evidence is all in plain sight - it's volcanic activity. Here only a deep understanding of this simple concept is needed. And since there is an excess of internal planetary pressure, then when "shaking" from the middle through the created faults, this excess of internal pressure is extinguished in the form of gas emissions or eruptions.
It would be very foolish to understand magmatic eruptions on the planet's surface as isostatic equilibrium, which can occur with liquids and solids of the same specific gravity. Geologists have not done enough work on this yet.
Now, according to the above, it would be possible to give an answer to the question posed in a more concise and monosyllabic way.
The maximum number of phenomena on the Moon falls on the perigee and apogee because it is during these periods that the selenosphere feels in some places overloads of tension from within, that is, tidal stresses.