Yes, some fights do make shield/absorb useless. This is much more prevalent in TfB.
Actually, those fights are not. TfB's ratio of "damage that should be taken" (re: not standing in bad stuff and ignoring insta-gib and screw up mechanics) is actually lighter on the F/T front than EC, which was already easier on that front than KP or EV. There is no fight in TfB that has a boss that deals, in the vast majority (or even significant minority), F/T damage. Most of the bosses are, in fact, almost entirely M/R damage if you're actually doing it right. Writhing Horror's only real source of F/T damage is the spray that hits the raid when the tank isn't in melee. Dread Guard has the DoTs, which shouldn't stack up that high, the massive HM AoE damage mechanic, which is substantial but higher hp is less about tank survivability than healer output because it hits the entire ops group. Operative IX doesn't really have much except for the HM Disinfect mechanic, which is really just an "offtank required" mechanism. Kephess' only real source of F/T based damage are the electrical debuff, which shouldn't be on that long because you're supposed to cleanse it by running into the ground patch, and the nanites, which shouldn't really hit a tank and, if they do, are removed by using the given mechanics; beyond that, he just hits hard with M/R attacks. TfB p1's only source of F/T damage is the suicide larva (which you shouldn't take damage from) and the spit patches (which you shouldn't take damage from). TfB p2/3 will only have a lot of F/T damage if you're standing on one of the outer platforms; if you're on the inner platforms, it's all M/R damage with the exception of the irregularities and spit patches.
If you want to talk about some bosses that make Shield/Absorb useless, TfB really isn't a decent example. EC has a few, but only because said bosses are part of a 2 boss fight wherein one boss is pure M/R and the other is pure F/T (Z&T and twin tanks); shield/absorb is still quite useful unless you're using specific strats where tanks never swap to the M/R boss. Even then, you'll still require at least 1 tank in the group to have good shield/absorb for the M/R boss. Your best bet is to actually look at old content for boss fights where Shield/Absorb is useless: Soa renders pretty much all tank stats completely useless because all of the damage in his fight is F/T I/E: not even your armor counts. The only reason tanks exist for Soa is because they have taunts (and, honestly, you can do without a tank for Soa if you just have a DPS that can taunt). For KP, Jarg is pretty much entirely F/T I/E damage and, interestingly enough, still one of the highest damage bosses in the game even though he's pretty much entirely outgeared now. Beyond that, though, there aren't really any major bosses with massive preferences for F/T damage over M/R.
In the current tier of content, the old reasoning for stacking hp like crazy (lots of F/T damage) just doesn't really apply any more. The only reason you ever want to stack hp is if you've already stacked mitigation so much that the DR curve functionally reduces further mitigation contributions to negligibility, and, even then it's debatable as to whether you should actually need the higher hp since there aren't really any enemies that hit hard enough to justify more than 24k hp unless you're running 16 man Ops (wherein you'll want 27-28k hp to account for the higher damage spikes, which is still not all that much, considering grade 27 gear).