3.6.0 features a tweak to crispness of dynamic fonts. If you use the "keep crisp" option on labels using dynamic fonts and happen to scale the label say, from size of 10 to 60, you will end up requesting all sizes of your font from 10 to 60. This means 10, 11, 12, 13, etc, all the way up to 60. This obviously means a lot of texture memory usage.
There are some disadvantages to dynamic fonts.
1. They are buggy. Unity's implementation of dynamic fonts was never finished properly, and sometimes letters get dropped for no good reason.
2. They always increase draw calls since they can't be made a part of the atlas.
3. They can't be modified the way bitmap fonts can be. You can't add a baked shadow, glow, outline, etc effects.
4. They have no kerning information. Unity didn't deem it necessary to provide that info to scripts.