There are some high power metagame builds possible in 5E but they are the edge cases and simple interpretations which are not even against RAW will nerf some of them (no trading pact magic slots for sorcery points for example).I much prefer 1e/2e’s multi-classing to the 3e/5e multi class pick as you go rules but they both address different stories - the former involves someone who starts their career as two or more archetypes and the latter someone who finds a new calling as they go through their adventuring life. Both are legit but particularly the 3e+ version is a harder thing to balance, especially as more options become available.
I don’t think 5e hit quite hit the spot but I don’t blame them for it. But yeah, a lot of ‘sorcadins’ and ‘pal-locks’ with pretzel-envy storylines to make sense of it for my taste. I thought Ford’s take on it in critical role was a case where it actually made some kind of story sense. But at my table… not so much thought has gone into it… ‘Patron? Ohh uhhh… like you know…’
The multiclasses are more powerful no doubt, but they are not overly powerful IMO. They make the other characters less useful in combat, but not useless and some of the most powerful powergaming combinations are not even played often - The hexsinger and the Palatrickster for example can be pretty over the top powerful in combat but I have only seen one of them actually played.
Most of the powergame builds are kind of one-dimensional and not that good out of combat. The Charisma builds are a little of an exception, they may be good in social situations but they are usually outdone by a Rogue, a high level Bard or a Wizard using spells.