He calls out BASIC specifically because it was ubiquitous and often the only option on the machines novices would have available at the time. It logically follows that most programmers of that era, capable or otherwise, started on BASIC. Since he’s not here to tell us, I can only assume Dijkstra met the occasional exceptional individual who began learning to program in a more mathematically rigorous language during that time and was left with a vastly more favorable impression.

Remember, Dijkstra was a professor and he was an expert on teaching programming. He would have far more experience with the effect he claims than I do. I hazard to guess that is true with respect to you too.

And yes he’s obviously engaging in rhetorical hyperbole in the text you quote.