Most larger national organisations have non-BRMs. AUK, RUSA and Audax Oz have the highest non-BRM percentage in their calendars but Audax Italia Randonneurs is another.
Don’t forget that all BPs and all SR600s are non-BRMs. ACP itself recognises non-BRMs in their awards. Apart from SR600s, some of ACP’s cumulative awards recognise Fleche de France perms. By definition, perms are not BRMs.
There are significant advantages for organisations and riders resulting from including non-BRMs in their mix of events, including non-BRM calendar brevets. The major advantages are probably allowing for significant over-distance routes without time penalties and flexibility in adding to the calendar at comparatively short notice.