Allo and Duo were complimentary apps, their simultaneous release was necessary and had nothing to do with their adaption rate.
Meanwhile, everybody who actually tried to follow the launch was confused about why there were two, which ones did what, why there was no interoperability, why wasn't hangouts being replaced, "Mobile-first? More like mobile-only," and "Should we even bother? They're going to kill them both off in three years anyway."
It absolutely did hurt the adoption rate -- It would have gone much better if Google management had announced one communication platform and committed to making it their bet going forward.
They were hedging, and it was obvious. Nobody wants to pay switching costs to use a new thing if the creator isn't even confident in their new thing.
Really when we say google today we are 100% not talking about the place we are remembering.
Imagine if Microsoft had an Excel team and a "Spreadsheetr" team...
You mean as in a "Microsoft Office" team and a "Microsoft Works" team?
Ironically, Google had this circa 2013 with Hangouts. The mobile app did SMS, im, video chat, voice chat,. you could do all the same on the web or desktop programs, including sending SMS messages from your computer.
For a short time, Google had an iMessage competitor and if they had merely stayed the course, they would have much more usage today then their fragmented explosion of mobile apps today.
Instead, they keep trying to kill Hangouts.
I dare you to use the HN search function on comments and come up with a day nobody mentioned this internal career ladder inside Google.