Sure - the tool itself may not be particularly effective. No argument here.
It's essentially a signaling mechanism - how strong that signal is received can vary a lot.
In the case of Russia at least - it's dampened quite a bit because both India and China are not participating. While they're not outright supporting Russia - they don't find the current government so unpalatable that they're willing to break off economic activities (and again - this is not a value judgement either way... simply a statement of efficacy).
In my opinion - I don't really think sanctions are going to be terribly effective (I also think the price cap on oil purchases will not be effective), but people don't seem to grasp that a very real possible alternative is outright war. Which, at least personally, I'd like to avoid. So I'm willing to let sanctions ride for a bit and see. But I'm also in favor of providing more arms and weapons systems to Ukraine in the meantime.
that said... I also have a bunch of duct-tape, plastic sheeting, water, and some iodine pills in my basement - because while I tend to hope that all the nuclear powers involved here will act with some restraint, those items will be very difficult to acquire in the 15 minutes when I might really need them, and they're relatively cheap to buy right now. So picking between that and sanctions... again - I vote for sanctions right now.
