It pains me too, but Riot __can't__ and won't treat all classes equally

See, there are some classes that have essential role in game's design and balance - i.e. if marksmen are too weak, we immediately run into tank meta - skirmishers and juggs can bully tanks out of top, but they can't prevent them from dominating jungle or support roles. We observed this during last tank meta, which exactly coincided with 'adc in 2k17 lul' memefest. Mages, as another example, are the best at stalling games, with their long-range waveclear, so if they are too weak we observe extremely snowbally metas - like now, meta is extremely snowball oriented, even though the most snowballing class (assassins) is on the weak side. If tanks are too weak or too strong, we run into problems too - we either have 2 seconds teamfights or toxic tank meta with 2 champions fighting on sidelane for 5 minutes straight without any outcome.

If a class like that is too weak, Riot needs to react relatively quickly.

On the other hand, there are classes like juggernauts - they don't have any essential place, their playstyle was introduced only for the sake of introducing another potentially interesting playstyle. If they are too weak, nothing really happens - tanks don't immediately start dominating, because there are other classes to stop them, games don't become any longer or any shorter because juggs aren't really oriented for stalling or for snowballing, relevance of teamfights vs 1v1s doesn't really change because juggs aren't really oriented for any aspect of the game. It is obvious that Riot won't react as quickly - every balance pass has a cost attached to it (i.e. it has a chance to turn game to shit by overbuffing/overnerfing something), so Riot is obviously less eager to take that risk.

It might feel unfair, but it's just the way it is and has to be.

And before someone says that, no I'm not marksmen main jugg hater, I main juggs and tanks.