I will often use my ultralight setups here in the lake, and there are some huge bass here. But I'm not targeting them specifically. I'm primarily looking for the panfish species, Bluegills, Crappies, Shellcrackers and White Perch. Early this year I hooked a big Bowfin on that gear and a Crappie jig, and did manage to land it. Ultralight tackle can handle some bigger fish, but it's not ever going to be my first choice for doing so.
Some of my other spinning rods are designated as "medium" action, and even they may be lighter than some would want for chasing bass. They were also bought with panfish in mind primarily but I can use them for bass. They're composite rods, so more fiberglass than graphite or whatever materials are used. I don't worry too much about backbone with those rods, as they're like using some of the baitcasters that I use for crankbaits, they bend a lot, but still have plenty of backbone, but agree if I'm really concentrating on bass, I'll use medium heavy rods instead. You don't use a BB gun to hunt big game, so using the right tackle for bass or any other larger fish, should be part of your mindset. That mindset should also include being capable of landing fish quickly, and releasing them quickly.
I also very much agree with Dale that finesse means lighter lures, not necessarily lighter tackle. I'll use 1/4 oz jigs as a finesse lure and can easily cast them with the medium, or medium heavy rods I have. I have two baitcasters that casting 1/4 oz with them is no problem at all. With some of those outfits I can cast 1/8 oz lures too, just not the same distances.
Just like with that Bowfin, and it was around 2 feet long, we can't predict what might strike our lures, but we can make good choices for what we use when targeting specific fish species and for the conditions where we fish. In the past, I liked the ultralight gear for catching White Perch, and would occasionally hook up with a small Striper. The tackle handled that fine, but again, would not be my first choice for targeting them specifically. I enjoy fishing with the ultralight tackle, but only within specific types of water for small bass or when targeting panfish species and when I want to target bass now in this lake, I don't even consider using it.