As far as responding from aliases, I haven't figured out a way to do that in my mail client (Mail.app), though I am able to accomplish it in my provider's web interface.
this allows me tighter control on a case by case basis and I get all the benefits of Office365 business.
No overhead of creating addresses, you have an infinite address space for your account to play with freely.
More mail providers should offer such a workflow.
With aliases, I can drop the alias and you can not easily guess my real email address.
Just depends on what you want, or what you use it for.
With Fastmail sets this up automatically if you let them handle your DNS, though you can (obviously) disable it.
You're still correct though, your solution is more secure (and also what I use). It's always possible the form you submit automatically strips the +whatever from your email silently. I believe facebook does this (at least when checking to see if the email you're using has already been registered).
I moved to wildcard forwarder on my own domain so that *@mydomain.com get forwarded to my main email account. This gives me all the tracking I want and I can ban addresses if needed.
That still gets me the zero overhead and practically infinite addresses with none of the downsides of gmail--and I can easily change my main email account as an added bonus.
For my alias management, I wrote a script to add and delete aliases and reload the MTA. Makes it super easy to do. Long time ago I would have to go through the process of creating a fake hotmail/gmail/yahoo/etc email address if I wanted to do something similar. This way is much nicer.
Way too much maintenance. This solution is easier.
The email aliases will forward a set number of emails, after which they go to /dev/null. You can white-list senders who you want to continue seeing emails from.