Yeah, I was a bit mystified by your reference, because my groups used the Complete books extensively, but rejected the Players Option books and never used them.
I was only acquainted with Mastery rules from set 4 of BECMI.
We got the books (used them for the reference above), but by then had shifted back to our BX/BECMI hybrid (when we played A/D&D at all in the mid-late 90s). I think of them sort of like 3.5E's
Book of Nine Swords -- they actually addressed things (martial weakness with Bo9S, character customization and varied gameplay for the PO series), but came out late enough in the edition's cycle that most groups had already rucked together some house solution by that point.
The Mastery rules in BECMI were a little like that for my group (playing as the set was coming out '83-86). They came out in the Master Set, purportedly for levels 25-36. I think we picked it up with characters in the 16-20 range, and found out it had rules for characters going back to level 1. By then, we'd already figured out a method to keep fighter's useful past the point where they got major benefits for levelling (mostly hordes of retainers, pet blink dogs, subjugated dragons, and what-have-you; plus whatever magic items were the real class features at that point). We looked at the rules (and the special symbols on the chart), retroactive picked them for our characters based on their level, and promptly mostly forgot about them.
Anyways, going back to the actual point:
The other thing that the Complete Fighter’s Handbook did, if nothing else, was make the most scalable martial class in any edition of the game. Single-class fighters using the mastery rules can seriously scale with level and continue to contribute to combat unlike any other edition.
I feel like base AD&D 2nd edition did that pretty well. Fighters suffered in earlier D&Ds when they only had one attack per round, all the ways that got fixed were pretty effective. Complete Fighter (or PO:C&T) handed out bonuses here and there, but not so much that I feel it outpaced the basic bonuses that loot gave*.
*and here I have to state that (IMO) the treasure table was part of the fighter class features in all TSR A/D&Ds.
With just PHB AD&D 2e you could get regular specialization with a melee weapon*. That got you 3 attacks/round at levels 13+. Combine that with (ex.) a +3 weapon and gauntlets of ogre power and you were throwing 3x 3d6+11 or 4x 1d12+11 damage against that dragon you are fighting (and enemy AC did not seem to scale with level+bonus, so you hit quite a bit). That's pretty effective damage output considering AD&D hp.
*+1 hit, +2 dmg, +1/2 attack per round
**4 if you dual wield, more with haste or speed weapons, etc.
***although the dragons I used in my example did get a huge boost from 1E
Moreso when one remembers the alternative classes also contributed less. Obviously Mages took off at those levels (given that the
'suck at low levels, be great at higher levels' model for them was deliberate at that point). However, given they were still fully Vancian*, were pretty fragile, and perhaps most importantly people actually used 2e initiative (subjecting them to spell disruption), they often spent a round contributing by 'staying alive and searching through their loot for a magic item which might be helpful (because none of their spells prepared were pertinent and/or they couldn't find a safe spot to cast).
*and unlike 3e or BX, the rules for buying/making scrolls to fill out the spells available were a lot more hit-or-miss