I've been running into a lot of maxed players with hangers full of pink star everything with no pilots on any mechs. I don't care what it's called, it's legal cheating tuned into the game by the programmers. The programmers allow this for the mindless spenders to keep spending.

You went up against someone with no pilots and the most basic mods and you lost?

For example..... 25K + 25% of pilot and implants is the same as 31.25K without. The combo to get to that point makes no difference.

Running 3 megamechs and a 2-star M.D. is SP dropping.

Not sure specifically about this case, but in general a part of the confusion is that "SP dropping" can mean "tanking" which is what you described or "running a lower SP hangar than a player is capable of". The latter can be perfectly balanced but many people still call it SP dropping.

Also, lacking any further info such as the composition of this hangar, to me it looks like the main complaint here is about the matchmaking (a 6K hangar facing an 8K hangar), which I feel is a legitimate complaint.

All complaints about matchmaking are legit :D

Unless a player is being stalked, no-one would know if a squad is the best that a player can put out.

Also.... if a map looks like it's going to work better with e.g. a Bastion instead of an Eclipse and the player has ranked-up the Eclipse more... is that SP dropping?

I run weird mixes because i'm going after mech achievements. If people consider that SP dropping, they need to touch grass.