They support it moderately well enough for the current state of implementation on the global scale. Dual Stack pretty much is a necessity for things to function in the current scheme of things. Until at least the gaming companies ween themselves off of v4, the ISP's need to take measures to maintain good v4 performance (among other things, that is just an easy example).
The problem lies more in the low adoption rates across the board. While the US has made a lot of strides in recent years, we are WAY behind where we should be, and most of the world is behind us.
Here is an interesting article on the traffic levels:
Its been five years and still no native IPv6 DNS Servers.
Charter Communication's is really slow when it comes with any issues or improvements to IPV6. Charter Communication's finally issued a firmware update for the Wave 2 Router's in January 2019 to fix the IPV6 routing issues. My guess is it might be years before we see Charter Communication's create a proper IPV6 DNS Server.