They did change the process recently, from what I’ve seen.
They used to offer the “captcha” option. Out of the last 5 times I’ve tried to create an account, I’ve only seen the captcha option once. Take that anecdotal data for whatever its worth.
I don’t know what goes into determining whether they offer you the captcha or not. I’ve gotten the captcha option with my VPN on (which seems like the most likely “fake account” trigger) and I’ve gotten the “email only” option when VPN has been off. 
As for emails on sign up - Proton says in their privacy policy that they store a hashed version of the email you use to sign up, so they can prevent people re-using the same email many times. It’s possible for law enforcement to compel them to hash a specific email and see if that email is in their database and which account it is connected to.
I tried to use temp email services (like https://reusable.email/) and found it worked a week ago and was recently blocked. (Which makes me wonder if they are looking at the plain text version of the domains people are using to sign up to scan for things like this.) I think other temp email services are blocked too. When I try to use https://www.emailnator.com/, it also gets blocked.
Which means you just have to use a real email address, which sucks.
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EDIT: Actually it’s fairly easy to just get an email address on another privacy focused mail service, then use that to verify. As others mention below, you can get an account quickly on Tuta.com or Mailum.com and then use that to verify your Proton account.