I think it is a problem because it's such a large gain to caster, specifically Sorcerer power over all other classes. You can basically end some encounters round one.
That's not so though, because you burn through a relatively small amount of resources to prevent the party using up a ton of resources. Sure, that individual character might be weaker later on, but the overall party resource savings from completely devastating alpha strikes shouldn't be overlooked.
Two fireballs is 2x 3rd level slots and 2 (not 3, unless it increased in 2024) Sorcery points, which sure, is significant. But if the other characters are saved a bunch of spell slots and other daily or even significant short rest resources, it's a massive win overall. Particularly in attrition-heavy scenarios, oddly enough - it's actually much more significant there than in the "5 minute work day", where you'll regain all the resources for the party anyway.
I hope that makes sense, I can try and explain better - but powerful alpha strikes very often are big resource savers and help most in attrition-heavy campaigns.