I've just gone over 200 aliases and none of mine are blocked. Are you using a custom domain?

I found a .com domain helps with this. You can find some ugly ones for cheap

Ebay blocks me everytime. I checkout as guest and usually when I try to order from the same email again, it is indefinitely suspended for reasons they cannot explain to me.

Here is what you should have done. Get a cheap ass domain and signup for Zoho's email service which is totally free. I bought a cheap domain from them. The price is very reasonable. Then AI proceeded to make use of their free email suite service, which requires your custom domain (hence the cheap domain purchase). The free email suite gives you give free email accounts. Each email account in turn has unlimited alias feature. I use their email accounts each for different uses (work, social media, etc). For only 10$ a year, I do not suffer from spam, promotions and shit. I use a dedicated alias for cookiebeggars and registration mofos who won't let you see their content. Another alias for a pathetic spamming shopping site etc. They have a mail client for all platforms so no issue with accessibility. The email has calendar, bookmarking, note taking and other small managerial stuff too. I recomend this approach.