So I have written about this a few times, but always in the context of 5th edition.

With respect to buffing or nerfing, sometimes you need to nerf. That a fix that buffs will cause more problems than it fixes.

Some problems are quantitative- things like damage, and a bit of scaling to bring outliers (at either end) towards the middle works. Others are qualitative, that the act of doing something disrupts the game.

My favourite example is from one of my games (5E) we had a ranger. The ranger's thing was to be a wilderness guide, a scout, and a survival expert. This faced some challenges but the last nail in the coffin was when the wizard picked up teleport. The character that would shine on a three week trek accross the mountains just saw their area of expertise removed from the game.

How do you buff ranger to avoid this problem? Giving ranger teleport doesnt fix it - your class fantasy of being a wilderness guide is reduced from a few sessions of spotlight time to a few seconds of casting one spell.

To preserve one character's class fantasy another character need to give something up.

I think that this also covers part of the challenge - it is really context specific. Teleport is not usually a "broken" spell but it is in the context of stepping on another class' toes. Invisibility isnt often a broken spell but if you have a rogue that has invested a lot of their class abilities in being unseen, then it is. In this case a buff may not fix things but can help (letting high stealth rolls turn you invisible).

So yeah, nerfing is sometimes needed and even if you wanted to, not everything can be fixed by buffs.

Add to that, that if some spell or ability is causing balance issues in a game then players want to see it fixed. Changing half a dozen abilities that are not the problem ability won't have the same confidence boosting impact than changing the abilities that have been problematic.