If slack was so superior, then teams would have not gotten as far as it did.
Right - it was superior, but not
that superior - it should have led the market, but it couldn't, because it couldn't compete on price and therefore on ease of acquisition. Teams was just
there, like if people at a company wanted to do IMs, and they hadn't previously, they could just go to teams.microsoft.com, and boom, they had Teams, with full directory integration, with their existing security policies in place, and just start working immediately. Contrast that to a Slack deployment which involves getting buy in from some IT decision maker, contracts drawn up, approvals, several days of work from some IT drone getting SSO and directory integration working, ensuring security is sync'd, etc. Arguably, those are things that made Slack worse (i.e. not being the incumbent), but I don't think we should be in a world where new, upcoming players are not allowed to displace incumbents, or one where incumbents should be allowed to leverage their position to preclude players in new markets.
Internet explorer both became the big player and lost because of this.
Can you maybe think of another reason or reasons why IE is no longer dominant? It's not just because the competition was better - it's because it was legally prevented from crushing them. US vs. Microsoft from early in the BF's history, for example, and similar antitrust rulings in Europe. Without them, no doubt we'd still be on IE and the world would be poorer off for it.
Well right now people will spend $$$ a month for office instead of using Libre/OpenOffice that;s been pushed by multiple governments over the years. There is no file format lock in. There's no OS lock in either. Office is simply better then Libre/OpenOffice for a large portion of people and they show that by spending money on something you can do for free.
Yes, it is simply better, but again, imagine there was an even better thing out there that cost say $10/mo/user more than O365 costs the company now that would deliver say $8/mo/user in value over O365, but users just like it more. Should the company switch? Incumbency is an enormous advantage that I think you're discounting. Just having Teams
available unused, in a lot of instances is enough to preclude a Slack rollout at a company, let alone if someone discovers it exists and just starts using it on the side. MS did a lot of things to growth-hack Teams, and its success is representative of that, but free is the secret sauce.