Not really, since CSS frameworks are just tools like any other. They abstract away repetitive tasks; and they lower the barrier of entry for devs who aren't specialists in CSS. The tradeoff is you lose control over your UI (you are bound to the features of the framework) and it doesn't teach you all that much about CSS. When you eventually want to extend or modify what it's doing, you'll have to learn CSS anyway.
If you are trying to become a frontend developer (ie. not just a javascript dev but a full frontender) then it won't help you with that goal. If you never learn HTML and CSS because you rely entirely on frameworks then yeah in that sense yes the frameworks will make you a bad (frontend) developer.