That sounds like a benefit to me :)
However, I think that's due to the general lack of interest in Lisp. You can see the C++ community has a similar ANSI standard and updates it every few years.
> Massive fragmentation in the compiler ecosystem
I wouldn't call it massive. They are pretty consistent, up until things like POSIX and FFI APIs. Let's agree there is some fragmentation. Isn't this still a better situation than if nothing was guaranteed?
Scheme is suffering from the same issues. Scheme is standardized, but implementations end up being incompatible with each other in subtle ways and the level of fragmentation is very painful. Scheme does get some updates unlike CL I guess, but all of the implementations either don't implement the the modern standard, don't have useful extensions for real world programming or are simply immature and don't have enough people working on them to get them into a nice state. In practice it's very difficult to use Scheme for anything non-trivial because of these issues.
I would much rather have no standard at all, and a single high quality implementation that everyone targeted instead of the current mess for both CL and Scheme. Until we get a new dialect that solves these issues Lisp is going to be more or less dead and irrelevant.
That would be Chez Scheme [0], maintained actively by Cisco, a company that you may have heard of - who also use the language extensively.
Racket is porting to using Chez, because it is the industry standard, it's performant, and rock solid.
The GNU alternative to Chez is Guile. Emacs can run with Guile, and Guix is built on it. It's got a fairly large community.
Outside of Chez and Guile, there are implementations and communities, but comparatively, they're tiny. Those two are the only big names you need. Like GCC and Clang for C. There are other C compilers. But you only need to know those two.
I think it already happened in 8.0
1. the standard covers everything you wished it would cover
2. every implementation implements the standard, with no bugs
3. the standard doesn't itself contain incoherent or contradictory things
Standards are a tool, not magic interoperability sauce.
The standards implying binary compatibility rules are about ABI (application binary interface), which usually depend on the ISA (instruction-set architecture) or the OS (if any) being used. You cannot have the unique one once there are multiple ISAs/OSes supported. Even when you only want to rely on some external "exchanging" representations not tied to specific ISAs, there are already plenty of candidates: CLI, JVM, WebAssembly... Plus there are more than one executable (and mostly, runtime loadable) image formats widely used (PE/COFF, ELF, Mach-O ...). You will not have the unique combination, and any attempts to ensure it "work across compilers" in that way will likely finally just add a new instance not fully compatible to existing ones, making it more fragile.