That is absolutely true if like you say, "is used correctly". That being said, in my opinion, the Lansky (with the old style clamp) is best suitable for flat ground pocket knives with a blade length of up 4" and the Lansky is still my system of choice for my Victorinox knives and most of my other small traditional knives. Larger knives can of course be done but it wouldn't be the best system for them.
Unfortunately, a lot of people have no idea what they are doing and do not use it correctly as can be seen in most of the videos about the Lansky on Youtube. Any system can be misused of course but it seems to happen more with the Lansky. The new type clamp that does not clamp smaller knives very well so that does not help either. I think Lansky made a big mistake when they changed the clamp and in the process transformed a perfect system into a crappy system.
The WE is arguably the best system on the market but also the most expensive. A Pro Pack II with some additional accessories will easily cost > $ 1000.- and would be best suitable for larger tactical knives and kitchen knifes. Smaller knives can be done especially with the optional low angle adapter but it is not the best system for those.
The KME fits nicely in between both in price and capabilities. Compared to a Lansky diamond set, it is about twice the price but just a fraction of the price of the WE. It can handle smaller knives as well as larger knives and with all the available accessories you can tailor it to all your needs.
I have all three systems as well as a few others which is of course a bit insane but I consider it a hobby and as we all know, hobbies are usually expensive

I have no affiliation with any of the brands and have good experience with all of them so I have no reason to recommend one over the other and I can only try to tell what I like and do not like about the various systems but what works very well for me might not work for you and that is why I usually buy it and try it for myself and than keep it or sell it if I do not like it.
What I can also say about the KME is that I have been in contact with them a number of times and I very much appreciate their perfect service. They are a small family owned company and they care about their customers. This might or might not be important to you but like it very much. I have good experience with WE customer service as well so no complaints there either.