I like how a year and a half-old thread more than doubled it's post count in like 6 hours today
On the point of the thread though... I think a lot of it has to do with flavor honestly. Samurai occupies a very specific mind space that doesn't fit into many campaigns easily without reskinning (totally doable, but when people want to play a 'Samurai' they want to play a Samurai, not a reskinned Samurai as a Western Knight or something like that.
Battlemaster OTOH is versatile, generic, and applicable to any kind of setting, even one where Samurai is a "normal" fighter.
Thematically as well they both occupy a similar space as the "rounded fighter" with BM getting proficiency in artisan's tools and Samurai an Int/Wis skill. Samurai wins here though because it gets proficiency in Wis saving throws.
Battlemaster is slightly more powerful earlier, so it also sees its peak in the levels where most games play or die.
Samurai is super powerful... eventually.
I mean the nova potential is staggering at level 15 if it is really optimized with Fighting Spirit, Action Surge, and Rapid Strikes, GWM, Polearm mastery, and if you took magic initiate or multi-classed a bit to pick up Hunter's Mark or some such...
Assuming Hunter's Mark is up before combat
Round 1 = 3 attacks at advantage + Action Surge 2 attacks at advantage + 2 attacks Rapid Strike + Bonus action attack (Polearm master) = 8 Attacks for 7d10+98+1d4+14+8d6... oof, that is just round 1
