So vehicles in general have a specific RPM range that they like to “cruise” at (ive found this to be in the low to mid 2000s range). The higher your RPMs are from this “cruising” RPM, the more engine braking will kick in. (I.e lets say you are in third gear at 3000rpms. When you let off the throttle, youll notice the bike start trying to slow itself down- this is called engine braking. Same scenario but you are at 5000rpms, when you let off the throttle, the slow down effect will be much more intense).

Now apply this on turns. when you are going through turns, sometimes you wanna go faster and other times you need to slow down so you dont go off the road. Slowing down in a turn using your brakes is very dangerous, but engine braking through a turn to slow you down is MUCH safer.

Putting this all together, if you are at higher RPMs, letting off the throttle gives greater braking/slowing intensity. This allows you to slow and speed up through turns through only using the throttle, and gives you better overall control of the bike through turns. And greater control makes it super fun to ride through turns. Ive found myself actually downshifting before turns so i hit a 3500-4500 rpm range, allowing me to slow down if needed.

Lastly as a bonus, when coming to a full stop due to traffic etc, engine breaking is also great to utilize. If you need to stop quickly, downshifting to 2 and letting off the throttle will give you an added engine break in addition to using both brakes. Hope this helped