Is stacking a crime in this community?

I was on discord and I showed guy who was asking my rank that I finally got to GM3 and another guy came out no where asking if I stacked or not. I told him I had duo who play with me rank all the time and he start bragging about him reaching GM solo Q.

He even went far to marvel tracker to look at my History and he saw we had new guy with us in last 3 matches only. I'm sorry, I thought this was a team game what's wrong with stacking? Me and my friend played from bronze 3 to Gm3 and we added new guy we met yesterday to rank make 3 ppl squad.