Why does the world need MatrosKa Video file? That's probably where acronym MKV comes from. It seems to be a container.
But again. If users have to convert it to other video formats, then why bother to put them into a MKV in the first place?
What is the world's motivation for wanting to put videos into MKV?
What is the specific advantage?
What is MKV's reason for existence?
If MKV is so troublesome, would the world eventually choose another better container?
Is MKV useful for video companies hosting video websites BUT
NOT so useful nor practical for end users who want to Watch those videos?

As most of us here now have a slew of GAOTD video converters that are confusing the heck out of us with their claims, could one of our more advanced video experts point the rest of us in a direction to learn some of the concepts and skills in this area so that we can make informed choices of good convension practises to achieve good results?

That would really be helpful because what is generally coming up on Google search amounts to nothing more than advertising touting each and every converter out there as the best ever conceived and used by film professionals worldwide (especially in Hollywood ... where one must assume some newbie bought what they are selling). Knowledge is becoming unfortunately rare these days on the Internet.

is this one similar to WinX HD video converter?

Very easy to download and install

Unfortunately this program will not convert AVI video as it claimed--pity!

Interesting timing for me. I'd just used a freshly updated "Format Factory" to convert an MKV to MP4. So I installed this converter. I found it used half the number of mouse clicks than FF. (OK, one rather than three!) It was much faster in the conversion. The resulting MP4 file was significantly larger than the FF file. Going into the properties of both, the Dimo file had much higher quality audio. That's a matter of settings and when I matched FF audio settings with Dimo the resulting files were about the same size. After matching audio, the Dimo was even faster than FF. Having said and done all that, I'm not sure my ancient ears can hear the difference. Dimo audio settings can be reduced and the result was a file about the same size as the FF. In addition to the MKV conversion, the program has other tools and stuff which I didn't try.

The obvious question that immediately comes to mind is:
Why get a premium one-trick-pony video converter for MKV, when there are several good free converters that extend their functionality to most formats, e.g. Handbrake and Format Factory?

Until this question is satisfactorily answered, one would logically expect demand for products such as this to be limited.