That's grand until someone runs a dictionary spamming attack on your domain. One of the interesting complexities here is if you forward to gmail from a domain, and there's too much spam, it'll blacklist your mail forwarder as a spammer.

(n.b., I've done something like this for ~nearly 20~ 23 years, and I've scaled back to prefix+tag with some aggressive blocking of email addresses that have been leaked/sold)