If you play alot and didnt have a stockpile of year one parts you have probably run out of parts by now. I get several legendary weapons and exotics each week and never have enough parts now. Of course I spend most of my time currently the last few weeks running Iron Banner, Crucible playlists and the raid so not that many normal drops. Also legendaries used to give you like 5 parts guarenteed on Decon, now they often only give two, some blues and greens only give one. Each node on most guns cost ten to level one perk, so Lets say depending on the gun anywhere from 40 -60 weapon parts. You can play a whole week and unless you are running strike playlists or POE, or just farming patrols for hours you often times cant get enough parts to level all your gear. Especially when your constantly infusing. I was one of the unfortuante souls that burned through massive stacks of mats during house of Wolves and old Iron Banner trying to get all the perks I wanted on my guns. so that didnt leave me with many once Taken King came out. I had just enough to make it through the first couple weeks and have been struggling to keep enough weapon parts on hand ever since.

People used up their parts trying to reforge their Legendaries in year one

Yea that's true as well... Well almost 2x. It's 3v5