BST is essentially a more advanced process than the older types of blacktop. I’m no expert (obviously); but, I do know that it works, and that it’s way better than bare gravel. It’s also better than old-style tar surfaces. The fact that it often costs less than bare gravel can make it a no brainier. (Asphalt or concrete is more cost-effective, and better for high-traffic roads. Gravel is cheaper for seldom-used back roads. BST’s sweet spot is secondary roads with low to moderate traffic.)
The biggest problem with seal coating is that the road surface is like ball bearings for several days after the application of the tar and pea gravel. I had an adventure on Land’s End Road near the ferries one year on my motorbike. The signs warning about the recoating of the road had been removed, and I came around a corner a little bit hot... No damage, but I sold the bike 2 weeks later. Skeered the bejeebers outta myself!