The reason for this limit, at least on modern systems, is that select() has a fixed limit (usually 1024). So it would cause issues if there was an fd higher than that.

The correct solution is basically 1. On startup every process should set the soft limit to the hard limit, 2. Don't use select ever 3. Before execing any processes set the limit back down (in case the thing you exec uses select)

This silly dance is explained in more detail here: https://0pointer.net/blog/file-descriptor-limits.html