Do they ever recover or is it pretty much a career killer?
*And do they recover better than one would after LL surgery?
Anderson Silva was never same after that. But then again, the incident happened when he was 38 where a decrease was to be expected regardless of the leg break. And Weidman, it seems that he's been losing fights since 2015 so let's see if he can get back to his prime again and win fights, then that would mean that the leg break didn't really take anything from him.
Either way, what happened to them isn't really comparable to what will happen to LLers. As someone else has said, the risks of LL have more to do with the stretching of the soft tissues.
However, we see in soccer all the time. Players were never the same again after some relatively minor knee/ankle surgeries even without such gruesome leg breaks.
In short, my conclusion is generally speaking, MMA leg breaks will affect the athletic performance to an en extent, but not as much as CLL surgeries.