I don't expect that I'll be able to get them to give me a top spot for an ad saying "Concerned about Microsoft's tracking policy? Mozilla Firefox is here", or "Still using Edge? Why not just get the original -- Google Chrome is here'.
Do you consider that shady too? If not, how do to you distinguish the Microsoft case?
But at least where I'm from, it's explicitly forbidden for radio stations (in fact it's illegal for any company) to run any kind of comparative advertising that denigrates a competitor's product. It's OK to show off your product, and it's OK to compare your own product to another company's, as long as you're transparent about what's compared and under what conditions. But an ad that mentions a competitor's product just to denigrate it would be illegal.
It would be okay for KBBL to advertise its news program. It would also be OK for KBBL to run an ad saying "Our program has the fewest fake news on the market", as long as they they tell you how to verify the claim (i.e. what numbers they used, who came up with them, how they came up with them, and how you can get them, too). But if they ran an ad saying "Still listening to WQHG-FM news? Tune to KBBL instead!" they'd risk having their license withdrawn.
It's definitely not pretty common precisely because it's illegal :).
So for example it's legal to show an ad saying that Edge is faster than its competitors, but you have to write a small note somewhere that says who measured that and how.
(Technically I think you can even call the competitors by name, but virtually no one does it because the public doesn't really appreciate that. Most companies will, at most, give a subtle hint).
It is, however, illegal to show an ad which simply says or implies that Firefox is somehow worse than Edge, or that no one uses it anymore, or that it's old, or whatever, without explaining how you got to that conclusion. It's fine to say that Edge is the most popular browser and link to a page about the study that showed it (or the study itself). But without the numbers, you're not allowed to do it. The studies in question are rarely truly objective, but they do offer useful data points.
That's intended to ensure that a company which is perceived as reliable or trustworthy cannot abuse that position and engage in false advertising.
This is a pretty good example -- among non-technical users, who make up the vast majority of computer users in the world, Microsoft is perceived as a solid and reliable company (and, the whole ads and data collection thing aside, it's perceived that way among technical users, too, yours truly included). Their word carries some weight, and non-technical users are likely to take their word at face value.
The way your comment was phrased I thought that you were saying the shadiness comes from it being a Microsoft ad on a Microsoft medium which does not accept ads for competing products.
In wider terms, Windows is very much not like a radio station. A radio station doesn't broadcast advertising for their competitors' shows, but it doesn't broadcast competitors' shows, either. If we're to apply the same laws that apply for radio stations, then they should apply under the same conditions: Microsoft can advertise their programs all they want -- but then they shouldn't allow running their competitors' programs, either. Let's see how successful Windows is without Photoshop, AutoCAD, 3D Studio Max, Matlab...
Windows is marketed and sold as a general-purpose operating system. I think it's reasonable for users to expect that Windows will treat all legitimate programs the same, regardless of their origin. That should include access to the operating system's advertising channel.
Using your foothold in one industry (operating systems) to discourage competition in other spaces (browsers) certainly is a grey area. Microsoft has been through a pretty similar lawsuit before, on exactly this topic, and that didn't go very well.
Is something Google would totally do. They've been pushing Chrome with the search home page for years.
I'm not sure what the adequate reaction here would have been. Should I have added a "P.S. oh yeah by the way Google is also doing this, don't forget to hate on them, too?" line in my original reply, for completeness?
In fact Google did it worse by blocking browsers purely by user-agent to key google services like maps to block the entry or Fire devices or windows phone devices.
Both cases aren't acceptible and both should be punished imho.