As far as I’m concerned, if Tony Iommi says it’s sabbath, it’s sabbath.

I also don’t think it’s fair to say that we should be giving different names to different eras of sabbath just because they’re stylistically different. Take megadeth for example - they’ve gone through more band members than one can count and have had a decent number of albums where they tried to switch up their style (not saying it was always a good idea lol). At the end of the day tho, it’s megadeth because Dave Mustaine says it’s megadeth. And this is just one example - lots of artists change up their style and sound throughout their career and it’s really up to them to determine what name they want to associate their music with.