I don't think I will have a hope in hell of winning credits in a ready-go at legend tier (not least because of my clubs) but have won credits in an "open to anyone" ready-go. I know that differs to a proper open tourny but does show it's not for sure.
I agree that level is often the greatest factor in competing. I've won credits in "open" ready goes as well, but the primary factor for that was the high number of wd's and enough low level entries that don't realize what they are entering. I'm just saying that if you look at "open" tournies, TL's are usually ruling the top 10, shooting rounds I haven't even been close to yet.
I do think, to your point, and specifically since WGT put in the sandbagging restrictions, that equipment should be tier based and not level based. This seems to make a lot more sense. At least make it so some of the top stuff is available to legends if they reach legend before the level to open the stuff.