An IMO is rated for switching under load, let's clear up any misconceptions or confusion some might have about the IMO. If you don't believe it, then contact the fella in this video and maybe he will clear that up for you.
As for the original video I linked and the following video in the next post, it mentions that if an inverter or isolator has RSD, then the addition of another isolator is redundant and not needed. If you have a string of panels like most of us do on a ground mount without any method of shutdown, then yes, you will need to add an isolation device for disconnect. I think some of the manufacturers of micro inverters and isolators are pushing for this to be in the code to increase the sale of their devices.
If you have rooftop solar, you are required to have isolation to meet the disconnect requirements for fire fighter safety at the module level. Ground mounts do not have to meet this requirement. Preferred method to keep costs down is still ground mount, for me it is not a hard decision to make. Those with limited real estate most likely will have to use roof mount and meet those requirements.
In AU, the requirements are different, this post here shows what they have been doing in the photo.
https://diysolarforum.com/threads/solar-economy-is-it-healthy.72148/post-959326 In the following post, it was stated that Finland had changed the requirements for rooftop isolators.
This post relates the majority of fires on rooftop PV was caused by isolators.
https://diysolarforum.com/threads/solar-economy-is-it-healthy.72148/post-959636
From what I have seen thus far, it appears the manufacturers of RSD devices are pushing for rules to use their devices, even if those devices cause the majority of fires. As for fires related to devices that copy the IMO, I would say those devices were not made to the standard the IMO meets. These are the import copies most people purchase to save a buck.