As a base I'd personally rather base the 150lb girl who was locked out & stayed tight than the little flyer who falls on my head 100 times because her little legs decided to give out. Yes there are plenty of little fliers who know what they are doing but in my opinion (just my opinion) little fliers know they are little and have no problem falling on your head because they know they will be caught every time. Larger fliers tend to knock everyone out on the way down so they try harder to stay up. Of course this is not always the case and I will say it again there are plenty of amazing little fliers out there! This is just from my basing experiences.
I've heard this from more that a few bases out there. Technique is so true.
Lots of times the lighter weight flyers aren't told enough to use proper technique for just the basic elements. They know that the bases are strong enough, so there are times the light weight flyer will not use a really big arm push off to get up to that extended position, or the rely tremendously on their back spot to reach high on the back of their legs for their elite skills, or rely again on that back spot to caught all their weight during a show and goes.
It's tough for this little ones when they move on to high school and college level teams where technique is so important (just because everyone is the same age and just about the same body structure.)