I thought it was a great speech precisely because she didn't link herself to Biden. At this point it's clear that Biden is not going to get enough young voters to win the election so he has to win center-right voters to bridge the gap (which he seems to be doing effectively). AOC linking herself to Biden sadly would endanger that at this moment in time.
My hope is that in the next 4-8 years, AOC can gain more of a national presence and show how the ideas she advocates for are not "radical left" ideas but are instead ones that help Americans as a whole. The GOP have defined her in a successfully negative way to the average American who has heard only a few sentences about her so the messaging has to improve for her to move up the ladder.