Totally true, but controllers are relatively interchangeable for these types of motors. A BLDC motor like almost all of the e-bike manufacturers have settled on

Totally true, but controllers are relatively interchangeable for these types of motors. A BLDC motor like almost all of the e-bike manufacturers have settled on can be controlled by any BLDC controller. If manufacturer X goes belly up and I need a new controller for my Manufacturer X bike, I can use one from manufacturer Y. Of course I might need to replace the controls, but If I can access the DC power source, and the three windings on the motor, I can make that motor spin with a variety of available controllers. The same is true for a lot of bike parts; If a fancy click shift derailleur kicks the bucket after manufacturer support ends, you can get a different one. You may have to replace the handlebar controls, but the whole bike isn't bricked by any means.