Underneath the hood other serverless technologies like lambda are running lightweight VMs running linux. Therefore they can easily accept any linux compatible container and they can run it for you in a serverless way.
Cloudflare Workers are running modified Node.js runtimes. You can only run code that is compatible with their modified Node.js runtime. For Cloudflare to be able to offer a product that runs arbitrary linux compatible containers they would have to change their tech stack to start using lightweight VMs.
If you want to run Node.js, then Cloudflare Workers probably works fine. But if you want to run something else (that doesn't have a good WASM compatibility story) then Cloudflare Workers won't work for you.
Not to be pedantic, but its not a modified Node.js runtime, it is a wholly custom runtime based on V8 directly. They're working on some Node.js API compatibility, but its not at all Node.js[0]
To quote directly:
Cloudflare Workers, however, run directly on V8. There are a few reasons for this. One reason is speed of execution for functions that have not been used recently. Cold starts are an issue in serverless computing, but running functions on V8 means that the functions can be 'spun up' and executed, typically, within 5 milliseconds or less. (Node.js has more overhead and usually takes a few milliseconds longer.) Another reason is that V8 sandboxes JavaScript functions automatically, which increases security.
Underneath the hood other serverless technologies like lambda are running lightweight VMs running linux. Therefore they can easily accept any linux compatible container and they can run it for you in a serverless way.
Cloudflare Workers are running modified Node.js runtimes. You can only run code that is compatible with their modified Node.js runtime. For Cloudflare to be able to offer a product that runs arbitrary linux compatible containers they would have to change their tech stack to start using lightweight VMs.
If you want to run Node.js, then Cloudflare Workers probably works fine. But if you want to run something else (that doesn't have a good WASM compatibility story) then Cloudflare Workers won't work for you.