People did that a lot to get new free accounts from disposable email services (You can generate 100 images/mo for free). Around 15% of signups were disposable email multi accounts (40% of email signups).
I use email verification API for this. It states to make decisions based on public email blacklists and lists of disposable emails. Cleary it's not perfect
And labeling a domain as disposable, when it's clearly isn't, sounds a bit strange to me.