D&D 5E Eldritch Blast Mulitclass Clarification

[seebs]

Huh? Strength of a caster is directly tied to their experience as a caster. I think I've said that, hence why my houserule is to tie it to their experience as a caster, not a noncaster.

I don't think that's quite right, though. Most of the measurements of strength-of-caster are things like save DC (character level). There's level of spells available, but that's a separate question from how powerful any given spell is when you cast it.

Same with everything else, for the most part; class levels give you new powers or abilities, but your overall abilities are for the most part getting their effectiveness determined by proficiency and abilities, not class level.