It's called minimalism, Ilan, don't let it unnecessarily perturb you.
https://www.youtube.com/watch?v=qXIR2AH9zng&list=PLA88E8VkVUDodyYkRa-xrLNOuHuRwg_rEhttps://www.youtube.com/watch?v=z_CKwRjD6rI&list=PLA88E8VkVUDodyYkRa-xrLNOuHuRwg_rE&index=2I used to avoid shifts too, because my jazz bassist teacher force-fed that concept to me. It backfired badly, I remember a gig where a guy quipped afterwards: "
Your bass player ain't doin' much, ain't he? Always stayin' in one place." For someone who was actually quite busy on bass, I took that as an insult. I don't recommend it unless you are a studio musician. Live, people, want to see you move around on the fretboard. I realized the errors of my ways and today I slide around liberally, more than I actually would need to. As a bassist, they can't really hear you, so you have to draw their attention via other means to make them realize you're actually doing something.
And of course you could do fine in a lot of bands - AC/DC, Judas Priest, ZZ Top, The Ramones, Motörhead, Mötley Crüe, U2 to name just a few - with just two strings.