I think the stronger player might still be favoured to win, because the gap from 0 to 1 stone isn’t the same as from 1 to 2 stones.
From 0 to 1 stone is 6 points, but from 1 stone to 2, if passing is worth about twice Komi = 12 or 13 points.
Anyway, realistically if you always had players available at your level, then maybe there would be no need for handicap.
In real life though, in person and online at least on western servers, you might not always get a game (quickly) at your rank.
If the options are play no game or play a game with a stronger/weaker player, which some people are reluctant to do anyway, then maybe a game with handicap is better than no game.
Some people don’t want to play a game where they’re sure to lose, but equally some people don’t want to play a game where they’re sure to win. It depends on their motivations.