Perhaps Tom Warlick lacks precision in his timeline, but there can be little doubt that the Briarhoppers influenced Bill Monroe. I emphasize the word “influenced” because Bill was interested in expanding his career in the 1930s Charlie and Bill days by getting onto WBT in Charlotte.
I have interviewed J. E. Mainer, Jr. (born 1924) several times over the past 12 years, and he claims he was witness to Bill and Charlie stopping by to visit his father, leader of J. E. Mainer’s Mountaineers, at his then-home on Harris Street in Concord, NC, the mid-1930s to get ideas on how to get a spot on WBT where J. E. already had a regular show. As we all know, Bill and Charlie eventually did appear on WBT.
It is difficult to think of a scenario in which Bill Monroe was not aware of who or what was playing on WBT in the 1930s and even later, whether he was in the studio at the same time or not, and that certainly includes various configurations of the Briarhoppers.
To say the influence of the Briarhoppers diminishes Bill Monroe’s role as the Father of Bluegrass is no more valid than saying Pendleton Vandiver and Arnold Shultz were the fathers of bluegrass. An influence is just that.
As for three-finger banjo picking, I would imagine the appearance of Snuffy Jenkins with Mainer’s Mountaineers and then Byron Parker’s Mountaineers would have had as much influence on listeners in the region as the Briarhoppers.