> 2. Why did they proceed to have half a dozen different messaging services?
Because they're different in ways that are not reconcilable into a single service. For example, considered just through an identity lens, you have:
Talk, which was a federated service with federated identity. Hangouts which was a centralized service with only Google accounts. And Allo which was centralized service using external identities (phone numbers). You can't do all of those, but need to choose one. And none of them is the obvious single correct choice.
(Hangouts and Chat are very similar though. But that was a completely transparent migration too.)
Or to put it another way: Why does Apple have both iMessage and Facetime? Because video + voice is different from text. Why does FB have both Messenger and WhatsApp? Because one uses FB accounts, the other uses phone numbers. Why has Microsoft made a dozen different messenger apps? Because what consumers wants is different from what corporations want.