Range Finder ??? I use the Mark I Eyeball. Have two of them and they work well.
Seriously though......I believe that if you know your rifle and know your load and, most importantly, know your capabilities and keep within them then you won't be shooting at a gadzillion yards anyway.
I know that about 300 yards is the extreme limit of my capbilities.....unless I'm shooting at a horribly obese elephant

.......and I zero to a PBR of around 250 - 275 yds then I don't have to worry about how far out it is because I will not take a shot beyond the length of two footy fields plus a little bit.
But then again, I can see the need for another you beaut gadget like a range finder on occasion. So everyone to his own....if you want it and need it....fill ya boots......and if it makes you shoot more goodly then so much the better.
Cheers, Vince