Whilst I agree and sympathise with people on how difficult it is to change your primary email address (been there), the outcome will be better for them. They are no longer wedded to an ISP purely because all their mail goes there.

To liken it to something more tangible; when you move house, you need to change your mailing address. For renters, that can be often and is just as painful. Or when your phone number changes and you have to update your contacts. The difference here is who is pulling the trigger; the end user vs the provider.

Gmail is a great option, as is Proton Mail for the security conscious and tech savvy.

This isn’t to excuse the ISPs; it’s a shitty move on their part and the people using these mail accounts will likely be older technically challenged folks, but it is a logical one from a technical perspective. They may have also inadvertently taken the only thing away that’s creating stickiness between them and their customer and driven them into the arms of another ISP.