In addition, the company doesn’t invest in growing and retaining the rest of the development team for 20 years until said developer is near retirement, then finds that they need to hire 10 developers because 2 need to replace said person and 8 need to redo everything they did.
I use Slack for personal projects and Teams for work. I think both are fine. The main reason it made sense to use Teams at work was because there were a number of products in use by different teams. IT had Slack and the rest had Zoom. Zoom was raising their costs and we already had Teams as part of 0365. So it was either buy Slack licenses for the entire company or just get everyone on Teams. It was kind of a no-brainer and it was hard to come up with a convincing argument to pay for Slack for everyone other than “Microsoft bad”.