Thing is... imagine they had announced "Thanks for being part of the gmail beta. We learnt a lot, but have now decided to close GMail. You have 3 days to download your emails and find a new email provider".
A lot of people would have been very pissed off, even though it said 'beta'.
As I remember, it would have been very odd for them to do that in 2008 or 2009 when it was so immensley popular. But that was 4 or 5 year into it's life, well beyond the typical lifetime of Googles products.
Them shutting it down in 2005 or 2006 would have been annoying or disappointing like the shutdown of Google Wave but understandable.
It's all about brand expectations. Google is synonymous with unreliability because they don't have another brand to shoulder that association. It used to be "Beta" but no longer.
The point is that their "release stage" marking was always fantasy land. Yes, I would be pissed if they had shut down GMail after 4 years, regardless of whether it was marked "Beta", because by that point it had a ton of users and clearly a ton of investment.
A big problem is that nobody believes their designations anyway. GMail was in beta for years when it was obviously a mature product, while "Of course we're investing a ton in Stadia..." only to shut it down a couple months later.
It’s impossible to go back in time and tell, but I bet lots of companies were opting for Microsoft Exchange/Web Outlook around 2007-2008, because Gmail was advertised as beta.
If they had removed the beta label sooner, they might have attracted businesses to GSuite sooner?
It’s a fine line to walk: you want to iterate quickly on one hand but some users need stability on the other.
A lot of people would have been very pissed off, even though it said 'beta'.