I have to disagree with this. Any email service that costs several dollars per mailbox per month is way too expensive for most people who tend to have more than a few email addresses, including shared ones. In many cases these may not be conducive to be trimmed down using aliases.
Take a look at Posteo.de, mailbox.org and Runbox.com. All of them are highly privacy focused, been around for several years, and also provide email for a low price. With prices of hardware going down, even those prices sometimes look high when you see the storage quotas, the low number of aliases (except Runbox), etc. (I concede that hardware is just one part of the solution, but see what Migadu.com says on that front).
Setting up a family of users even on Fastmail’s lowest tier (without own domain support) would soon become quite expensive, not to mention the standard plan.