For users of general purpose computers this is caused almost entirely by closed-source software. Most of the architecture-specific code is part of the operating system, and by the time you're doing an architecture transition the OS itself runs on the new architecture. The third party applications largely aren't dependent on a specific architecture but they're compiled for one.

With open source you could just recompile for the new architecture. Linux has always run on just about every one under the sun and the user largely can't even tell the difference. But if you don't have the source code you can't do that.

Closed-source systems could avoid this by compiling to bytecode, which is essentially what Android does, so transitioning to RISC-V would be much less trouble there than it would be for e.g. Windows.