So we all agree, that while free, and while cool (the Hotmail of the 2000s, Hotmail was hot in the 90s esp with teenyboppers) that Gmail accounts don't have the advantages that ISP mail has.
I really like GMail because of the great functionality it offers, the integration into other Google platforms and the fact that you get about 7Gb free storage per email address, and it's free. The added features are quite helpful and convenient, very easy to check emails on your cellphone since just about every mobile OS has some sort of GMail application available. It also has a very good spam filter, I simply never see any spam in my Inbox.
But yes, it has distinct disadvantages. Bye bye privacy? Google use software to run through your emails to look for keywords to display ads you may be interested in. Some see this as advantages but since I use ad blockers, I see nothing anyway.
When compared to emails hosted by e.g. a web hosting company: Nevermind hacking, when GMail goes down (and it has) then you're immediately stuck and you cannot really call anyone for support, you can only hope they will fix it soon. Since you don't pay for the service you don't really have any right to complain either.
Also, if GMail for some reason decides to suspend your account, you could have a very hard time following some lengthy process of resolving the matter.. With a local hosting company you pick up the phone and sort it out and if that doesn't work, you can get in your car and drive there as a last resort.
That said though, I haven't had many problems with my GMail account(s) but I use it for personal emails only, for business I'd rely on a HOSTING provider like Hetzner where you can use a specific domain name. I wouldn't use ISP email because then you're locked in with that ISP. If you change your ISP, you'll have to change your email address as well and that can be a hurdle if you have 1000 people you have to inform about it.