I mean, they crush competitors. Not so much partners and clients.
These are all tool makers and basically competitors.
And frankly for the vast majority of them they actually bought the alternatives. For example, they bought Skype for messaging, they bought Great Plains, etc.
They ran Skype into the ground by compromising on the quality of the end user-experience - just like they did with MSN Messenger - and the current desktop Skype client is an Electron app (at least this way Linux still gets supported...).
Skype was in prime position to be the best way to have free voice and video-calls between iOS and Android phones and the wider Internet (seeming as FaceTime is Apple-exclusive and Hangouts seems unpopular) - I don’t know what happened but WhatsApp ate Skype’s lunch and got bought by FB and the rest is history.
Skype on my iPhone X is just painful. I use it to make cheap PSTN calls when I’m abroad and simple things like switching to Speakerphone mode takes 2-3 seconds and involves opening the iOS audio output list (which has an animated opening for some reason) instead of every other app which has a single speaker button. This is but one example, of course.
They could have bought Slack, but they competed with MS Teams instead - but doing-so awfully because they still don’t have multi-tenant support in the client. Thing is - I can’t say that competing with Microsoft has made Slack any better (case-in-point: last month’s always-on WYSIWYG editor debacle).
IIRC Skype peer-to-peer architecture was a very bad fit for smartphones. For instance text messages in Skype were sent directly from client to client, requiring the two PCs to be up and running at the same time for the communication to happen. It was brilliant for PCs running 10 hours a day, making Skype infrastructure very light.
Now take two iOS smartphones, where Skype will only run when the user is focused on the app. The peer-to-peer link was simply not going to happen. Skype brilliant peer-to-peer architecture simply didn't work anymore. This is why Skype was so late to the party.
Skype went from peer-to-peer to centralised right after Microsoft bought them out - this was before modern smartphones got popular - and to my knowledge the smartphone apps were always centralised.
These are all tool makers and basically competitors.
And frankly for the vast majority of them they actually bought the alternatives. For example, they bought Skype for messaging, they bought Great Plains, etc.