Don't think its as simple as sliders or no sliders.
Sure a lot of race teams don't run sliders now well not always, some modern tracks that motogp and superbike go to are built to modern F1 standards and have tarmac runoff so the bike will continue to slide and slide if they are installed. Older tracks built to older F1 standards, have gravel or grass runoff, and yes the slider or if not the slider something else will catch the ground and dig in before leading to a flip. But without the slider it will be the hand controls or footpegs next.
Sure look at Jonatan Rea's crash at Monza race one this year, sliders or not the bike slid nicely until it hit the gravel then it was flying through the air and had not front end left. Then look at some of the crashes from Portimao most people just jumped back on the bike in the tarmac runoff and carried on, including those with sliders and those without.
Personally I don't run them, I think unless the frame is designed for them (not the other way around) there is no real way to be sure they will do what they should do. Also I believe in not crashing
