> surely it would be extremely beneficial to have at least 1 open source filesystem that has good support across all platforms
The comedy of this is that there are actually plenty of FSes common to all three of these OSes, they're just not considered "modern"; FAT32 is still the most commonly used FS for interop, even as it shows its age with poor support for very large files (2+GB) and file systems, but you also have ISO(9660) and (the best answer we currently have) UDF supported by all three OSes natively and openly without patents or other licensing restrictions. The latter two are not commonly used as read/write filesystems, but have zero inherent restrictions on being able to be used in such a way.
However, the problem has been largely supplanted by having a fast and well-functioning network and people moving to "The Cloud" for, well, everything. It's hard to know how much of the Great Cloud Migration is caused by these kinds of intentionally engineered interoperability fails, especially the monumentally stupid exFAT patent... It's interesting to ponder given the people likely to complain the most about filesystems today are people who want to move large files (4+GB) between OSes without anguish, where the network is still just too slow to handle the task well.
The comedy of this is that there are actually plenty of FSes common to all three of these OSes, they're just not considered "modern"; FAT32 is still the most commonly used FS for interop, even as it shows its age with poor support for very large files (2+GB) and file systems, but you also have ISO(9660) and (the best answer we currently have) UDF supported by all three OSes natively and openly without patents or other licensing restrictions. The latter two are not commonly used as read/write filesystems, but have zero inherent restrictions on being able to be used in such a way.
However, the problem has been largely supplanted by having a fast and well-functioning network and people moving to "The Cloud" for, well, everything. It's hard to know how much of the Great Cloud Migration is caused by these kinds of intentionally engineered interoperability fails, especially the monumentally stupid exFAT patent... It's interesting to ponder given the people likely to complain the most about filesystems today are people who want to move large files (4+GB) between OSes without anguish, where the network is still just too slow to handle the task well.