I am following your logic, but as someone who’s been using a 2 in 1 for like a decade, I can tell you everyones hair needs are different. I’ve used them separately as well and it really does not make a difference for me.

Even the cheapest shampoo and cheapest conditioner out there, used individually, will easily outperform even the fanciest combination.

But I really take offence to this line, absolutely not true. The cheapest shampoo will dry up/irritate your scalp, the cheapest conditioner will make your hair feel like an oil spill.