>The Mojang accounts weren't great for security. No 2FA or anything (just security questions), and if you lost your account / it was stolen, you were pretty stuffed. The only way to recover it was to present the transaction ID of your purchase of the game to support, which most people don't have and you were never told to keep. I saw lots of people get permanently locked out of their accounts.
It was in fact super easy to just search my email Inbox for emails from Mojand and find the proof or purchase.
With MS I have 3 fucking accounts and not by choice, they bought Skype and Mojand and forced me into their super shitty system, I spent 30 minutes 1 year ago to migrate the Minecrtaft accoutn and more then 30 minutes a few weeks back to login back into Minecraft because I needed to detective my way to figureout what Microsoft account they connected to my Mojang purchase.
I hope in a few years someone leaks what greedy motives were behind this forced migrations, probably to sell more shit.