Thing is if Ryobi was to make top quality whipper snippers people wouldn't have to keep buying them over and over again. There isn't enough money in quality products most of the time these days. We live in a disposable society - No-one wants to spend $500 on a whippersnipper they will use once every 6 months when they can spend $80. Different kettle of fish for commercial equipment of course.
I find the biggest issue is and always has been poor maintenance. The trimmer heads especially followed very closely by the carby - people fill a 5L can with 2 stroke, fill the tank from it once and leave it in the shed. They only use a tenth of the tank before the fuel breaks down and it blocks the jets.
The carbies are so small that the jets are tiny and I cannot see (I have quite severe sight issues) what I'm doing so it can take around 5 hours for me to properly clean out a carby and then spend another hour or so trying to get the mixtures right.
I never bother with whipper snippers. When I get brought one for repair I usually just talk them into selling it for scrap metal and buy another one.
My 2 cents worth.
Pete