I would have completely agreed with you garirry only a few years ago. I was a die-hard local mail client user that really hated web-clients. I have used nearly every decent IMAP and POP client over the years on Mac, Win, and Linux and finally got to the point where I was spending far too much time managing problems and incompatibilities with client software. Considering that in 2015 the majority of users use several devices to access several accounts for email, contacts, and calendar, the most portable and compatible solution is modern, standards-based HTML5 webmail clients.
The problem with local mail clients like Apple Mail is not completely Apple's fault (or Mozilla, or Microsoft's). The problem is that Google doesn't do completely standards-based IMAP, or calDAV, or cardDAV. It's not just email that's the issue, it's the complete package. I finally got fed up with one client on one platform misbehaving and corrupting my contacts or email on the server. And, even when it was all working well, an update to any client on any platform could then cause a major problem.
So, a few years ago I jumped ship, removed all the client software from my desktops and laptops, and embraced webmail. I've never looked back. It works flawlessly no matter where I am and from any OS, and I'm no longer worrying about my contacts or calendars being corrupted either. I do still use the iOS native mail, contacts, and calendar Apps because they have always been very reliable with all major providers.
