I spend an inordinate amount of time at my C# day job adding documentation comments about exclusive access and lifetimes and ownership… things which are clearly important but which dotnet provides little or no useful support for, even though it has a perfectly good garbage collector. The dotnet devs were well aware that garbage collection has its limits, especially when interacting with resources managed outside of the runtime, and so they added language features like IDisposable and finalisers and GCHandle and SafeHandle and so on to fix some of the things GC won’t be doing for you.
I’d happily use a garbage collected language with borrow checking.
Careful not to conflate things like hash trees with Blockchains. The former do get used for stuff like certificate transparency logs right now, because it is a sensible technology. Blockchains could do exactly the same thing (because they’re based on the same underlying principle), only with much more expense and waste, so there’s basically no point.