^ True that. Of course, going into a battle shounen manga just for the yuri is plain silly. But the yuri scent is obviously in the air: the care and deep concern of Ochaco for Toga is very real and established; and Toga "falls in love easily with everyone" in her own words, so that certainly includes Ochaco who she lets in so close to her heart to have this chat. So there is canon reciprocal feelings between the two, not good enough to build a romantic relationship (which needs more than just feelings for each other to form and function) may be, but that's still more than a significant chunks of all yuri ships around. People are not hallucinating seeing this ship.
Also, the serial shippers don't even care about canon, shipping is just fun.
(also, as supporters of LG**B**T, we understand that some people are bi and monogamous so they stick with people of one sex one at a time, so about half of the times they are with people of the other sex, right? Such detail might never get explicitly stated if it's not the focus of the series, but I find it to be way less of a headache about the whole 'bait this bait that' debate to just handwave it that they are bi and monogamous)