Why do you expect them to crack down? The intent of disallowing working on tourist visas is to protect the local labor market. Digital nomads work for foreign companies and don't get location based market benefits that would be restricted to locals (consensus among the various communities seems to be that having local clients was a big no-no), so they add no pressure to local labor markets. In regards to the local economy, digital nomads are nothing but tourists.

Rather than cracking down, the current direction is legalization. Countries where digital nomads are common know what's happening and they ignore it as it's beneficial to them and are now legalizing to get an even larger slice of the pie (by attracting those who were previously fearful).

Others have mentioned the issue of housing stock, but regular tourists are actually more inefficient in that regards (very seasonal and short stays. Think about how many empty room-days most hotels have).