That's why Tesla have an FSD subscription
The fact is, some people want account-locked, others car-locked. Basically, if you are buying a new replacement Tesla, you want account-locked so you can transfer your investment, but if you are buying a new non-Tesla replacement, you want car-locked so you can recoup some of your investment in the car resale. There is no right or wrong here. The only real issue is those people who have paid $$$ for full FSD and have yet to receive the feature (and may not see it
at all before they sell the car). This probably does warrant some form of value transfer to the new car (though Tesla would no doubt argue that this happens when they sell the old car WITH the full FSD feature).
People would like both, however car-locked is far preferable if you get one, both because you definitely want that if you are switching to another car, but you also want it if you no longer feel FSD was a good purchase.
If you want to sell your Tesla and get a new Tesla with FSD, you should be able to sell the old car with FSD, and get a premium for close to $12K when you sell it, which you can use on the new one you buy. Of course, as always sales tax is a killer on private used car sales.
Now, in theory FSD should sell for exactly $12K in the used market, because it isn't "used" and does not depreciate while you have it. In reality software products that are "used" will sell for less than new, though it's not entirely clear why they do, unless you are going to get less support etc. with the used software but that's not the case here, one would think.
So, to make up that difference of what you can sell it for and buy it for "new" you would like transfer. And to avoid the sales tax. It's in Tesla's interest to let you avoid the sales tax with a transfer, that makes you more likely to get it again.
Tesla FSD has generally been an unwise purchase. Opinion on the value of the early features is varied but generally quite low. I myself never use them except parking sometimes. FSD "beta" is not included with FSD and only given to some drivers, and it's interesting to test it out, but it's not useful as a product to make your driving experience nicer.
As such, if you have $12K, buy $12K of TSLA stock with it. If Tesla ever makes FSD work, your TSLA stock will go up far more in value than any price increase that might come to FSD. If they fail to make it work, your stock may go down, and so you would get a little less out of it than the refund you are owed -- however large that is as they will claim that some of what you paid was for navigate on autopilot etc. The stock is a more likely win, though when it's been up in the stratosphere that's less clear.