Nope but they do potentially have some of the drawbacks (the suspension performs differently depending on whether you're sitting or standing).
It's as good as negligible (7-8% stiffer when stood) to be honest. Means you're a little bit less likely to bottom it out when stood up, and when are you more likely to bottom out your suspension normally? When you're stood up going off a big drop…
I have owned a URT bike in the past (Orange X1 in 1996), and the Maverick is worlds apart. The Orange wasn't as bad as people made it out to be (the BB shell was pretty close to the pivot which helped) in fairness. URT's mainly have a bad name cos of bikes like the Klein Mantra, where the pivot is in a ridiculous position. They're not the best suspension design by a long stretch, but to some people they have their place.