So a few points on this, because I mostly agree.
You can point to a handful of Muay Thai legends who also had boxing records, but for the most part their boxing records consist of them beating up 2w-7l fighters for about 30 fights before losing to a prominent name from Mexico or something to that effect. It's common to boxing in Thailand, even Srisaket had a record of mostly cans until he fought Chocolatito but it just so happened Srisaket really was world class. So while I do agree with the point that some of the old school thais boxed professionally, it's a point that IMO is over stated and exaggerated.
More on point though, I don't really see why its a question as to whether or not the jab is redundant. It's just not? Thais don't use them tons because Thais barely throw punches nowadays, but ultimately if YOU personally are in the ring as a fighter, scoring points is fine and all but you're going to need to know how to jab in order to set anything up. Especially if you never fight in Thailand, and most of us won't fight in Thailand. (The only person I can think of on this forum who actually fought professionally in Thailand is Frode).
Very glad to hear Lahkin shouted out too, LOVE his approach. Yodsanan Sityodtong too, great example of someone who knew where and when to use his power in Muay Thai. You half expect him to come out swinging but Yodsanan would needle with the teep a lot.
I think you absolutely should have an understanding of how to jab and how to generate power power in Muay Thai, because it IS under-used in the sport, especially right now. It wasn't that way before, but now it certainly is