We have several models of the routers you have in our own outdoor test network, and found that there are certain firmware versions (theirs) that are compatible, and others that are not.
We’ve updated our firmware several times to adapt to various 3rd-party routers, and have even gone so far as to expose autonegotiation controls for troubleshooting rather than introducing additional logic for specific vendors and all of their firmware versions. You can see how this would be moving target.
In some cases, the other company’s hardware or firmware just isn’t compatible for one reason or another, and for practical reasons, the switch addition is the shortest path to address the problem. It can resolve clock timing contention issues, and provide isolation - either logical or electrical in some cases.
In @Bryan’s case, he found a great way to add functionality. Nice! Our experience with Netonix switches has been positive as well.