Does UWP have a purpose, yet?
The last time I tried to make a UWP app was long before UWP was UWP. It was back on Windows 8 and, after a brief play, I scrapped the sample and went on with my developer life. The whole experiment can be summed up in one exclamation: "You can't do wot !?!"
So... it's now 2018 and I believe that the sandbox is a little more diverse and that UWP hands developers a little more power but UWP apps are still not true desktop applications and can't do everything. If I was to start a UWP based project, I would have to do two things. Firstly, I'd have to accept that I'd be locked in to UWP and the only way out would be a total rewrite. Secondly, I'd have to completely plan the entire foreseeable life of the project and be absolutely certain that UWP allowed me to implement all the features I would ultimately need.
Sure, I could do these things. Why would I?
Both of those sound like a lot of hard work and a lot of risk and I still don't see the benefits that UWP offers in exchange. It just doesn't offer anything that isn't already available elsewhere -- most of which I have used or experimented with in the past, a lot of which is cross-platform.
Microsoft are asking me to leave a known world of infinite possibility in favour of an unknown sandbox governed by arbitrary decisions. That's like asking someone to give up their somewhat aged but perfectly reliable Skoda in favour of a shiny new toy car. However awesome the toy car may be, it is still a toy!
The only reason I would ever use UWP would be if an employer dictated that I do so and even that seems vanishingly unlikely because UWP is not really suitable for business applications -- most of which now run in the browser, anyway, unless they need very specialised access to local hardware which UWP probably doesn't permit.
Oh... and on the LinkedIn thing: you can now send people a one-line voice clip saying: "You've got mail!". That's totally a use-case!