It looks like it was a good idea to somebody at the time when it was implemented. However it was never adjusted later when Intellisense, _Access/_Assing, etc. were implemented.

>It's a bit ridiculous - few properties are absent at the class level (left and top, but there may be others we haven't found yet) because they'll surely be defined for each instance (but what happens when they are added programmatically and these are left at default? We don't even know what the default is). So we don't see them in the PEM window, fine. But it doesn't make much sense for intellisense to hide them too when we're writing code. I guess it's pulling the list of visible properties from the same source, where it says "ooops, class level, show only this list".