Agreed, that is why I am a Taijiquan guy and only a Taijiquan guy these days. It takes time to get these things right and some simply do not want to take the time, which is ok, it is when they donāt take the time and then go about bad mouthing said style I get upset.
But with that said there are sometimes things are not as dissimilar as one may think....or wish they were... see Xingyiquan and JKD.....
Also within CMA you can find similar approaches within styles that are considered vastly different.... see Sanda and Taijiquan.
So a bit of cross training may help one understand things, kind of like getting a different POV a physics course that makes things more clear. But it is best, IMO, in those situation to have a real good base in a specific style, as well as being dedicated to that style, if one uses cross training for that purpose. One also has to be real careful with this approach because it is way too easy to start using things as it was shown in style B and allowing that it override what you were trying to figure out in style A.
Example: I can go train qinna that is used in Sanda that might help me get a better grasp on a qinna app in Taijiquan. And the Sanda app may āappearā easier, but in reality it uses way to much force for Taijiquan. It would then be my job to figure out how that is used in Taijiquan. Or if I am real lucky the Sanda approach clarifies what my taiji sifu was trying to teach me. That boot to the head, if you will, that I needed to make my brain work.
Or as I was doing recently, training with Wing Chun guys, not so much to learn Wing Chun as to get a better understating of how taiji would work in these situations. Some days I got pummeled and others I did ok and learned a few things. For one the Wing Chun approach to center is very different than Taijiquan...that I found very intresting.