It's definitely a slight learning curve (a few days at most for basic understanding and troubleshooting). I can't speak to complexities like routing protocol configurations.
But goodness, the infinite-subnets-of-same-size glitch is so amazing. I see companies all the time that struggle to subnet their sprawling enterprise. Different subnet sizes everywhere, fragmented networks, subnet migrations to try to defragment, so on.
Many orgs are so short-staffed and staffed with mediocre talent that they spend their days fighting fires and keeping their flawed current practices operating just well enough to keep the lights on and not cause outages or security breaches. Things like "optimizations" and "redesigns" of the IP stack, even in 2026, would be a 5-10 year journey without a dollar sign benefit attached to it. So they limp along until the transition is seamless and necessary or monetarily desireable.
It's only really a learning curve if you're an expert at IPv4, and try to apply your IPv4 mental model directly to IPv6.