I completely agree with you on this. Companies have to innovate or they die. To me Slack had plenty of chances to go beyond their initial product. Imagine if they incorporated Screen Hero into Slack and poured resources to reduce latency and better real time collaboration as if you were a feet away from your coworker. Would Microsoft be able to replicate all of that from scratch?

You also have to consider that if you're a startup you can be a lot more agile because you deal with a lot less bullshit. Microsoft probably has tons of red tape and they are also spread thin. Their design space is also restricted in that they have to follow existing patterns. Slack should have been able to roam the earth however they wished. But they didn't. Slack had the lead and momentum but they blew it.

I don't see Teams as necessarily a bad thing as the article implies. Every product we have is a derivative of something else. It fosters innovation.