ABA has been the only intervention which has worked for dd1. She has severe ASD, although these days it seems a lot more moderate than severe, thaks to ABA.
She was so severe, that when she was 4 (after 18 months of 1:1 support at preschool, and a year in a specialist ASD placement) we were told that she would probably never be able to learn anythig much (such was her non-responsiveness and the degree to which she was closed off from the rest of the world).
We knew that was bollocks, adn no way were we going to write her off like that.
She is 9 now, and has been in an ABA school since shortly after we removed her from the above placement (who clearly had given up on her). She is doing fantastically. She can now read and write (reading at about ORT level 5, spelling ability is close to my dd2's, who is in year 2), and hold short, clear conversations.
She is as far from robotic as you cojuld imagine, tbh. she certainly has her own opinion on things, and doesn't just take in what is taught as gospel!
ABA is the method by which she learns. what she learns (and the quality of it) is down to the quality of ABA she receives. Which is fantastic (and I hope she can remain in her school through secondary).
It is defintetly worth questionning the quality of ABA provision - there are some shocking examples of programmes out there. But ABA itself? it's just a teaching method (and a highly effective one if used correctly)