RISC-V Community: "ARM Architecture: Understand the Facts"
arm-basics.com
arm-basics.com
Where open source does benefit is a more timely and fair fix to a reported security bug. A company's closed source implementation may not be in as much of a hurry to fix security bugs if there isn't an immediate effect on the bottom line
Also, how's open source supposed to minimize fragmentation? Desktop Linux has a hundred flavors and even with a standardized ABI, there's no guarantees on a single binary working seamlessly across distros ( which is the reason for this like flatpack to exist)
Of course there still exists a long tail of alternatives, there is no stopping that in an open source world.
1. Arguably shifting to LLVM/clang these days. But note that clang for instance implements a huge amount of GCC compatible behavior (like commandline flags), instead of inventing their own.