Again, while you may want it to work this way, that's NOT what the Zwave spec calls out in terms of routing behavior. See this earlier note: Automated Cleaning of ZWave "Tortured Routes" - #14 by GuyMan - As the SiLabs radio handles the routing controller, and the spec is well established. This is consumer grade stuff, not OSPF or EIGRP.
Per the other thread, the best bet for "all on/all off" behavior would be multicast support in either ZW or Matter (that seems like a reasonable change to make on the HE side as useful additional capabilities, given that it works with ZB). But your not going to get the ZW routing algorithms changed, regardless of how non-sensible they may be.
As your noted, your getting down to the balancing act of removing many of the redundant mesh links, given your conversion of problematic ZW mesh nodes to LR. Personally, I prefer working with Matter (WiFi, but Thread is basically smarter/better ZB), as you have more specific controls and visibility (with TCP/IP and wireless APs, etc.), and Inovelli white dimmers are very capable given the last FW upgrades. That all said, the DA stuff you doing in Zooz, is likely the best option you have for "hubless/fast" dimmer controls.