It's not meaningless at all.
First off, if you're comparing multiple offers with similar salaries, equity considerations may be a good way to make a decision.
Beyond that, understanding how companies handle equity compensation can tell you a lot about their culture and treatment of employees. There are companies out there that are eager to answer these questions because they give generous stock compensation and want you to know it. There are also companies that will obfuscate and hide behind misleading numbers. I once had an offer and asked for more equity, only to be told by the recruiter that the stock was about to split, so I'd actually get twice as much (this is absolute nonsense, to be clear, and a huge red flag).
Lastly, with regard to your initial question about compensation, asking these questions absolutely can be useful to that end. When you're negotiating with early to mid-stage startups, one of the things that you can negotiate is your equity/salary split. I once took a pay cut from the initial offer in exchange a much greater amount of equity than I was initially offered. That was because I found a lot of positives about the company and preferred higher risk and more reward (thankfully it looks like that is going to work out very well in my favor, but obviously that was in no way assured). If a company's giving you bad answers as it relates to equity, you may well want to try to negotiate for a higher salary in exchange for less equity, so your financial circumstances aren't tied as much to the company's performance. Understanding equity gives you one more dimension on which to negotiate, and the more things you can negotiate, the better off you are.
There is this prevailing idea in Silicon Valley that you should just ignore equity and treat it like a lottery ticket, and while I think that is very good for financial planning, it is otherwise awful advice. Just because you don't have full control over the way things go with equity doesn't mean that you shouldn't educate yourself on what can be a meaningful portion of your compensation.