No different than any other game. First year of cod blackops guns are not available in black ops 2 or 3. Battlefield changes gins every year. Its called progresssion not regression
So it's not really comparable to Destiny as you take the same character through all versions, why not some of the weapons too? If the new ones are creative, effective and powerful people will still use them.
The character i have now is not the same as vanilla. U have new subclass, no light, and new armor. Have to look at yhe character as a whole, no just the being