For the record, they are not asking you to replace your Raspberr Pi computer, nor are they telling you to reinstall anything. They are only telling to to just buy a simple and inexpensive USB-extension-cable (that is preferably shielded) and connect your Zigbee Coordinator radio adapter via that USB-extension-cable to a USB 2.0 port on the same Raspberry Pi so that you can move the Zigbee radio some distance away from it and other electronic sources. This is a low hanging fruit fix that should be sorted out first before troubleshooting any further.
FYI, I wrote that linked guide plusxmany other Zigbee guides/manuals and have helped thousands of follow users in the community with similar issues causes by radio interference and/or poor reception. No one here is gaslighting you. Zigbee radios and the Zigbee protocol are extremly sensitive to electromagnetic interference and it it a fact that it really makes a huge difference to move the radio away from all electronic sources as they will basically act as radio jammers to Zigbee.
See this whitepaper from Intel (which specifically mention using the suggested workaround to put the wireless dongle on a USB 2 extension-cable) as well example video from Home Assistant’s Zigbee radio hardware developer showing how USB 3.0 is jamming Zigbee communication:
Once you have the Zigbee Coordinator connected via a USB-extension-cable then you have at least tried to remove and rule out the most common root cause of Zigbee problems which is radio interference.
PS: The second most common is by the way having too few good Zigbee Router devices as repeaters stategicly placed, so highly recommend getting a a few of those as well regardless.