RCTs aren't perfect. There's a bunch of problems with them, generalizability being just one. But you know what's even worse? Everything else.

Big questions are great and I'd be all for focusing on them if we were capable of coming up with reasonable answers. But all we've managed are DSGE models and they're about as useful as reading the lines in goat livers.

I'll take the RCTs thank you and with a side natural experiments. Duflo is the most significant economist of my lifetime. Thanks to her economics has some basis for calling itself a science.