I think you're wrong here, quite a few people took so called race bike for
very long trips like you would regular travel bike succeeded with no problems.
If you're not racing service interval actually can be measured in miles or kilometers and it's not that bad because they changed oil every 2000 km
or 1200 miles so it's doable. You get instead very light bike to deal with on the road. I was afraid about this aspect as well until I own my ktm 500 exc which appeared to be very reliable and adventure capable machine.

BTW, crf250l doesn't look good at all, looks weird at most.

You are correct about how reliable the KTM 500EXC appears to be. But it's still early days with only a couple guys taking the 500 on RTW type rides. I'm sure more will follow ... and good luck to them.

We all travel in different ways with different priorities.

But its true, traveling on a race bike will mean you can likely extend service intervals out quite a bit, as traveling is usually not hard on the machine. If the basic bike is reliable then could be done. So, instead of 500 mile interval could be pushed up to maybe 2000 miles? More?

But is this ideal?
Most raced based bikes are not well set up for carrying luggage. Some don't have large fuel tanks available, unless you spend A LOT on money. Many carry Rotopax or Bladders ... I'm not a fan of either of these methods.

Rear sub frames may not exist or quite weak. So not idea for panniers weighing 30 kg. or so. ... plus a top bag and other crap travelers tend to pack.

Some travelers like to camp (to save money I guess?) and LOVE to pack up their bikes like the Beverly Hillbillies. Race based bikes may not be ideal for the perennial over packers so common in our world.

My worry would be if you get yourself into a location where you can't find top quality synthetic oil, as required for many high end race bikes like the KTM 500.

And in addition, the rider will need the skills and tools to do the maintenance on the road. The KTM is easy ... a good thing.

But some bikes are more complex to do self service ... and they are not even race based machines. (BMW GS's, Ducati Multistrada, KTM 1290) Most require dealership computers to plug in for diagnostics.

I like the looks of both the CRF250L and Rally. Weird? Not at all. It's just not that different from dual sport bikes 30 years ago. so, both good and bad.

full synthetic is nit required, I use same oil as for my xt660z tenere, motul semi synthetic. Regarding luggage and frame, motonomad guys used fully loaded caoyote giant loop bag with no problem

Yes your absolutely correct, you, me, anybody can do just about any journey they want to with any bike. They manage to get comp. bikes to the end of the Dakar with less time for maintenance than on a road & trail trip. It's a case of where there's a will there's a way. True too you don't have to be stupid to do it either, crazy maybe, like crazy in love with "that" bike ! Or just crazy with a passion to do it. Yes it's true too that if your not racing stuff can be pushed out a lot on the mileage....This guy is one who is proving it :The Rolling Hobo (respect) But it does depend what you want from it, and all that work can detract from trip unless you want it that "hardcore". I'm a great believer in horses for courses and if your not racing you don't really need a race bike for most trips, although if you just want it that's fine. I used to race (road) 250's TZ's & RS's...loads of work!..Loved it at the time...Now ? I can't be arsed with all that when I'm on holiday, right now I'm struggling with the thought off going back to a chain drive instead of a shaft and all that adjusting etc.
Everybody is on a different journey or wanting to be and we're all at different points in our lives and our journeys, we're all different heights, abilities, age's and we all have our own idea of the perfect bike..and even that will change for each of us unless we keep doing the same old thing. I used to think my R1 was perfect for me I put so much thought, reading up and test rides into which bike would be the best for me before I bought that bike, and it was awesome at the time but now I've got a BMW. It's been almost perfect for what I've used it for too but now I'm looking at Husqvarna's because I'm thinking of changing what I do and where I do it..again. Some choose their "ride" because it's a gimmick, unusual etc. and it will sell books or whatever, I'm not really a fan of that but I can't say I blame them, there are so many at it nowadays. Generally though my thoughts are ride what you like, doesn't matter to me but don't presume I'm on the wrong bike because it doesn't fit your criteria... So if you fancy all those oil changes when you could be having a round the campfire feel free..I won't be jealous..I will when you hit that fire road and get to "let it loose" though