For the most part I agree with you. If your meta involves people playing 5-6 sb cards against dredge or involves leyline/wheel of sun and moon then yes it is probably better to be prepared for some hate. Similarly if your meta is very heavy on path to exile maybe a reanimate target like Iona is in order. Overall though, in an scg meta like this list was set up for, you'll see 2-3 sb cards from your opponents if that, and mostly you will be seeing relics and crypts. Neither of these cards are scary for competent dredge players and usually it requires two crypts/relics to really cause any problem so why bother siding in 3-4 ancient grudge and potentially some nature's claims just to beat them? Grudging chalice in the one game you might see it in 9 rounds is cool and all but you can recur ichorids and flashback dread returns without one drops, it just might be slower. Similarly while jitte can be annoying it is often too slow, this deck is consistent enough to dread return on turns 2-3 (thats testing results not random numbers out of my ass.) Simply put jitte just cannot keep up.
If your meta is gunning hard for dredge then bring in some reactive cards. If you play in a typical meta that does not have a high representation of dredge and dredge hate then you don't need slow reactive cards that cause bad keep/mulligan decisions and don't actually help you win. Dredge is one of the most unfair decks in legacy, embrace and take advantage of that.

