both STOS and AMOS/ AMOS PRO were indeed popular on the Atari / Amiga machines not only back in the day, but they still have a small but committed community of the game / util / app developers for those platforms today.  I've not heard much about STOS for years but there's been a various attempts to bring AMOS PRO  to the next generation,.   

STOS and AMOS were developed by François Lionet who's original idea was the make AMOS2 but couldn't get the rights, hence it morphed into AOZ   -   It's been a  while since I was following the development of AOZ, but it's basically a transpiler or sorts;  so convert input code to JS.    

 AGK (1 & 2) BASIC / STUDIO on the other hand compile to virtual machine.   For the web version the entire VM is translated to JS via enscripten.   So user code is interpreted on thier VM -> in the browser.    So there's pretty hefty penalty for the convenience.   I've done numerous performance tests with AGK revisions over the years and their VM /Runtime model isn't exactly a powerhouse.   My point being is that in order to write efficient code a developer needs to rely less on brute forcing and leverage more of the built in features.  

  None the less there's plenty of space for more such tools