OP: if you read among the lines of your own post, you will see, that the stem/root of the problem is not a min/max mindset, rather than having chassi and weapons that are inherently and utterly imbalanced to begin with.
Guess who will (ab)use the imbalances first: the cadet or the veteran?
Weapons:
Damage in big chunks with greater intervals or damage in a continuous stream?
The idea is that both should be valid options, but the reality is that the latter means exposure to burst damage and is suboptimal. Burst is king.
Now you know what kind of weapons you "should" equip, and consequently know that epxosure to them is bad.
Onto chassi:.
You know that exposure is certain death, so you cherry-pick the chassi with the highest mounted weapon slots/JJ-s in order to jump-snipe/hill-hump: Stalker, Highlander, Caraphract 3D, Catapult K2, Blackjack.
[Victors are kinda an exception, thanks to SRM buff and very high mobility (essentially the brawler Victor is the perfect medium mech

]
There you have it: optimum builds on optimum chassi. Even if you can't aim or pilot at all, you still can theoretically spreadsheetwarrior the builds yourself, or just read some forum pages/watch youtube/twitch and gain an idea.
Add completely fcuked up hit registration, hitbox issues and other bugs, and you have FOTM (or in cases flavour of several bloody months).
PGI wants to balance with heat, but instead of heat dissipation+overheat penalties, they went the heat treshold (without heat penalties other than simply shutdown) route as a design decision, and everyone and their cats figured out that alpha-striking is the best way to kill, instead of carefully managing heat by alternating weapon groups, weapons, etc. Now they bandaided the second approach with an overcomplicated extract of the first, and nothing changed, except that there are less AC40 boats, and the remaining macroed/stagger their fire to have .5 sec between the two shots.
I don't think that comp. players are to blame for this. All of the above are stemmed from bad design decisions and crap weapons from the get-go.