It is a part of the industry that has been entirely replaced by services, similar to web hosting.
This same situation happened on the web for Internet Explorer. Nearly every modern browser supported a set of standards that IE just wouldn't deal well with and so people did the same thing and made the websites work for all the other browsers and then used various tricks to get IE to play nice. Media Queries on the web were one such case. IE couldn't really deal with them and so people would make media queries for their sites and then create separate styles just for IE. It was a huge pain. I'm just curious to see how this extends now that we're back to a change like this in email. Outlook is now web-based and Microsoft is way better at keeping up with the rest of the industry but I can't help but think that there are still crowds of people using older versions of Outlook.
Thanks Google!
Maybe it's more a problem with how you use email if that's an issue you have.
Of course my 'anecdata' is no better than yours.