In theory, practice in theory are the same. In practice, they aren't. To the point, real science is hard. Damn hard, and always has been. This isn't new. If this were new, we'd be living for a thousand years and taking vacations beyond the far side of the observable universe.
Even things that seem obvious can sometimes break down completely when put in the crucible. And things that you thought before broke down may really not have. No less of an intellectual powerhouse than Feynman famously said that you are the easiest person for yourself to fool. People don't understand this, not really, because it isn't in their daily experience. Even if they're trained scientists or engineers, they learn a pattern of behavior, they ape it, and they say they're doing science or research, but put their work to rude scrutiny, and you often find they've just produced incestuous no-op statements because that subtle bit in their heads that should have told them to scrutinize themselves and justify their own assumptions never flipped.