There's definitely a multipurpose aspect to a lot of older martial arts styles, where they are no longer tested for their fitness in most practical senses, and so the form gradually degrades into purely being sport or performance. But the other side of that coin is that arts that develop a restricted kind of technique often do renew themselves when they are reintegrated into a practical system by someone with some design sense, and sport styles in particular allow subsets of fighting to be explored in depth and remain vibrant through competition, even if they are not "realistic".

Boxing, for example, is hugely restricted to avoid grappling and yet the fighters still try to clench up regularly. Actually staying on your feet, throwing punch after punch, is hugely unnatural. But boxers that learn enough grappling to escape submissions can cross over to MMA and do respectably well, because they have the skills to bring down someone at a distance.

Judo, likewise, is full of artifice these days. There are mamy restrictions on the types of holds, penalties to avoid stalling, scoring balanced heavily towards getting off an impressive throw, and a limit of up to twenty seconds to get a pin. But these restrictions also compel judo players to develop strategies for a quick, confident takedown and submission.

The styles that suffer, in contrast, are the ones that may have had relevance in the context of weapon fighting but are now mostly performance - the tai chis or aikidos of the world. Krav maga persists in part because its design works with the smaller knives that modern armed forces continue to use.

Ultimately, the point of training any named techniques is to develop muscle memory - what that memory is used for is secondary, and in that sense all popular systems succeed.

Wing Chun is also taught and used around the world in police academy & military camps. But that is not to say it is better than Muray Thai, and I don't see Muray Thai being used for this purpose.

>Growing up watching a lot of Kung-fu/Wushu movies from Hong Kong

The problem with Kung-fu/Wushu itself, it is for one people over idolise it, second being it completely lost most of its root in Mainland China during the 2nd World War and later CCP forbid the use of it. ( At one point they over emphasise science / Guns / technology and calling Wushu as old fashioned and not up with time during the Cultural Revolution, of course in reality CCP doesn't want to arm people with fighting skills ) Most of the Grand Masters ran for life and arrived to Hong Kong during that time, that quickly spread out as a culture and hence why later you see many Kung Fu movies from Hong Kong.

A lot of those fight scene coordinators from HK ended up coming to the US to advise Hollywood movies, my understanding is that it's definitively changed the quality of fight scenes (if you compare fight choreography in older movies vs the crazy stuff now).

So yea, it's looking like it's had a lot of success in theater but not in combat.

I think the purpose of the "do" disciplines is maybe getting lost somehow; it's supposed to deemphasize violence as a matter of ethics. This essay reflects my understanding well:

https://iainabernethy.co.uk/article/jutsu-vs-do

If someone would compile it this is the sort of report I would read (and pay for) gladly (i.e. what martial arts are used in military / police academies and the rationale).