The other downside is that us other drivers get to experience their beta testing in prod. Few things are as annoying as driving behind a Model Y where the adaptive high beams don't work properly, and getting flashed by every oncoming car for miles on end.
They did operate on a "continuous refresh" basis. However, it mostly stopped for almost 2 years now. Other than HW4 I don't think anything else is different between current models and their iterations 2 years ago.
Edit: mostly speaking about Model Y, as Model 3 had actual refresh recently.
The thing is Tesla operates on a "continuous refresh" model, they constantly iterate on all aspects of their design.
The downside of this is it makes supply chains for spare parts an utter damn nightmare, which is why spare parts are so hard to come by.