For me, Reels has never been able to zero in on my interests in the way that TikTok has. Reels mostly shows stupid, low denominator content compared to TikTok which is showing me math videos, videos about ML, etc.
Algo-feed only Threads means trusting the same sort of algo behind Reels and I am not convinced that it will work. Twitter allows for much easier bootstrapping.
Already, I am pretty turned off by how inundated Threads is with celebrity content that I really could not care less about.