So far every single opponent has been completely helpless against the hero and his 30000 year training in a stage 9+++ world. And now we're supposed to believe this random small-time villain's barrier was so powerful that he couldn't get in without the girl's ability weakening it from the inside first? The author wants to have the girl redeem herself and grow, but they can't give the win to her (cause the reader self-insert MC has to be the one to have all the glory every time after all), but her ability can't be completely pointless even though it seemingly is, because then she has no accomplishment to take pride in, so we just randomly make up this SUPER powerful barrier ability that the MC for some reason can't break, just to give the girl some miniscule significance. What I'm saying is, it's a little forced.