And while the game has methods to bring weaker characters up to snuff, like Tomes, Gloves of Dexterity, Girdles of Giant Strength, Decks of Many Things (which can also turn great characters into soulless automatons hated by every Devil in the Nine Hells!), a lot of DM's seemed pretty stingy with these, lol.
Conversely, they can be fairly anti-stingy if it makes something doable. Gauntlets of Ogre Power/Girdles of Giant Strength ranged from 0.2-0.4% of random magic item drops (of unspecified type) across oD&D and the two AD&Ds. Yet they seem to have been incredibly common both amongst PCs I saw in play (perhaps DMs not using the tables) and treasure in modules. I think part of that was because (ex.) Joe was really pleased with the fighter he was cultivating in terms of personality and social connections and other mechanical heft (like HP rolls and magic items), but was rocking that 13 Strength and was he going to lose interest.
Looking at the old Rogues Gallery and such I always figured that a) They were using more generous generation methods, and b) ability score-raising magic effects in dungeons must have been relatively common back in the 70s. Which also explains Gary's seemingly-insane rules for Wishes raising ability scores in the 1E DMG. 1 point per Wish up to 16 and then TEN WISHES per point after that or something similarly obscene. Wishes must have been coming out of people's ears.
Geezer and Chirine and a few of the old guard I've talked with have kinda indicated such to be the case. Gary didn't realize quite how destabilizing wishes would be, or maybe that people would save them up for 'permanent' mechanical effects rather than world-changers or get-out-of-a-jail-free cards or such. IIRC, several years ago Jon Peterson showcased an early copy of Rob Kuntz's Robilar character sheet of which someone had a copy. It had some genuinely improbable stats for 3d6, including some that had changed.
BITD, particularly if we used the '16+: 10:1' rules*, we tended to instead use wishes to get re-rolls for level-ups where we rolled low for HP. Probably not statistically beneficial (if you rolled a 2 on a d8, the reroll would likely only net you 2.5 extra hp, hardly worth a wish), but I think (as FormerlyHemlock alludes, above) a lot of the stat difference was psychological.
*my actual BITD gaming was mostly BX/BECM/AD&D hybrid play.
I think it's a solid rule for AD&D, though not really needed in OD&D, B/X or BECMI, which have rules for point-swapping to increase your prime requisite. OD&D also generally doesn't provide as many benefits for high ability scores (though moreso post-Greyhawk), and B/X & BECMI make useful bonuses available with stats as low as an 11 (Int for bonus languages) or 13 (Con, Str, Dex, Wis).
We found B/X's p. X51 pretty early and realized that each point of stat was useful for the generalized resolution mechanics (and used those quite extensively before skills came along). For that reason, we rarely used the point-swapping mechanic.
The older I get, the more I like oD&D (pre-supp. I) method, but then with B/X X.51 logic applied -- the primary way you got better at (ex.)
being a fighter was to
have more levels in fighter, and attributes/attribute checks mostly covered other aspects of the game that class, level, attack rolls, spells, and the like did not cover. Sine Nominee's OSR-adjacent
Worlds Without Number roughly follows that, and I find it very refreshing after both 5e and AD&D.