One could think you’re proposing this [leaving the EU] as an alternate solution. It’s not. And Brexit is the biggest proof.
This is not a random thing thrown around, though it should be noted that those more involved in this side of “EU bad” usually advocate for remaking the EU, due to the deep systemic issues rather than leaving it. I believe a more mainstream version of this idea is given a stage by Macron (AFAIK he mostly wants to remove the requirement for every country to agree to some things), but moreso from this angle some Pirate Parties (PPP for example) advocate for it.
Quote from PPP’s programee (translated by yours truly, though I focused on translating it as directly as possible so it might sound a bit weird):
More democracy for Europe
We, Pirates, call for a writing of a new EU treaty, which will replace all existing treaties, remove uncertainties and respond to the need of a democratic reform in the EU. This treaty must be accepted by the citizens of the EU via a referendum.
While this is quite different to “we should leave the EU” it reflects the concerns of those who say that due to policies like this. As far as I know, Brexit was caused more by Brits not liking economic policies of the European Union, though I am not that knowledgeable about UK politics.
TL;DR: you can say EU bad while still wanting an EU I guess.