I'm gonna be honest - there is no reason to play DS1 or 2 in current year. Outdated, clunky, outclassed by Bloodborne, Sekiro, DS3 and ER in everything. A newcommer can easily skip them without really losing any memorable experiences. Remember - those games were good for their time, they are merely okay now, and this is coming from someone who has played them all chronologically. FromSoft are one of the very, very few companies who have consistently improved their games with every sequel (except for probably DS2).
The most you could argue here is there's not much reason to do DS3 after Elden Ring, since BB and Sekiro are pretty different.