Especially since you can buy raid banners from multiple vendors... And barely 10% actually do raids if that much... Unless they're trying to do something stupid like give you so many banners you try to do a raid just to get rid of the damn things and wouldn't that be messed up...

Xur should sell or give a weekly quest for the harmonizers always. Also red borders can be farmed infinitely, so can always find a group to focus farm for the specifics through fire team finder if trying to finish the patterns asap. Not sure if the featured raid requirements are still in effect for older raids though, luckily finished my pattern collection as soon as each raid had them made available throughout the seasons.