I think thats not accurate. For me it also shows first match 2015 even tho I started 2013.
Also I have played with Buzz long time ago and I think it was before 2019, or maybe I remember wrong.
Also it doesnt really make sense to make an account in 2015 but play your first match 4 years later. But anyway at the minimum he has played csgo in some form in 2015.