What's notable is that string pinsetters have only recently been standardized (and that's AFAIK still an ongoing process), because they have been wildly inconsistent. USBC has a recent update here: https://www.youtube.com/watch?v=yDvb0VmlHDU
Ultimately, I much prefer free fall bowling, but if the choice is between "string bowling on a USBC certified pinsetter" and "no bowling", I'll choose the strings. It's not a completely different game (like Duckpin, 9-Pin, or Candlepin), and it's still good - but it's different.