Every athlete has skills that they are proficient at and others skills that they may struggle with but ultimately it is up to the organization and the coaches to add talent to the given team where they see fit. To say that if a certain athlete does not do jumps to back or tumble makes them not worthy of a Level 5 team is just plain wrong in my opinion but I have been seeing it more often and I don't necessarily think its fair.
There are many aspects to building a team and each member brings a certain skill set that can add to the teams overall performance so lets not "lock out" certain athletes because they may not have all the skills you might think they should have. As long as the team meets the requirements to max out on the score sheets there can always be a place for athletes that don't possess all of the "Level 5 Skills" if they can bring a certain skill to the team. I know of several level 5 teams that compete at Worlds each year that have athletes that don't tumble but are incredible as a base, back spot or flyer so they certainly serve a purpose for the team. If your gym is overloaded with amazing athletes that have all skills this is not a problem for you but I think that is likely a rare situation.
Not all major league baseball players can hit HR's or are the best in the field but they bring a skill that is valuable to the team and therefore they are part of that team and they are at the highest level of their sport.
For some of the smaller gyms it is not easy to fill a level 5 team because the number of athletes that have all tumbling skills plus the other intangibles are just not available. As long as the kids can contribute to the team and fill a need I see no reason to question why they don't tumble, do jumps to back or anything else. Let them go out, have fun and compete which is what this is all about. Please don't misunderstand me, I'm not singling anyone out who has already commented on this post I'm just giving my .02 from the cheap seats, I'll get off my soap box now. ;)