Yeah but there actually are distinctions between levels, or there should be. A 6 at Facebook will have different expectations to meet than a 5, presumably. The difference in scope between a 6 and 7 at Amazon (the approximate equivalent) can be considerable at times.
6-7 yes that’s the jump from SPD to staff correct? 5-6 isn’t much. Still design, meetings, owning some product decisions, driving the pursuit of well engineered projects and you get on with getting on.
Senior UX to principal, yes. Or staff. Whatever. Amazon has some amazing Principal designers and plenty who don’t contribute anything. I think the smartest designer I know there is somehow a 5. Leveling is weird.