According to Bethesda at that time, they announced it early to avoid disappointing their fans who might start endless speculation about the fate of the game. However it should be noted that while the game might have been announced, gamers should definitely not hold their breaths because it will be a long time coming.
This was confirmed when GameSpot spoke to Bethesda’s Pete Hines and ZeniMax Online Studios game director Matt Firor at PAX Australia where according to Firor, “The easiest thing is look at how it was announced; it was Starfield and then [Elder Scrolls 6]. You can go back and count the years between Bethesda Game Studios releases, and you’ll get the idea that [The Elder Scrolls 6 is] not coming anytime soon.”
HInes added, “I try really hard to manage people’s expectations. It’s not like ‘Fallout 76 this year, Starfield next year, and then TES6 the year after.’ The timeline isn’t any different. What’s different is just trying to be transparent and say, ‘Don’t freak out, the next thing we’re doing is single-player [in Starfield], [and] we are making TES6.”
So if you are looking forward to the Elder Scrolls VI, there’s still several years from that happening, so maybe you should put it at the back of your mind for now.