First of all , can I plead that we keep this thread focused on the issue at hand, not all the other myriad "what about x" issues with CMS.
Currently, CMS ends when a child is 18 or leaves full time FE (but not HE). Given that very few people are now able to be financially independent of parents until at least early twenties, especially with the current situation with rents, zero hours contracts, difficulties for young people to get full time, decent employment, AIBU to argue that the rules around CMS should change. The devil is in the detail of course, but realistically, many RPs will be hosting their adult children for 3-5 years longer than traditionally was the case. If the NRP is not willing or able to have them stay 50/50 should there be an obligation to continue to support them in that case, even if it was a direct payment to the child from whom the RP then elicits rent? I really don't want a bunfight or a "I left at 16 and never looked back". It's 2025, the world has changed and even the brightest, most driven kids are often still at home beyond the age of CB.