I've been on both ends of 1:1s. For a manager, they seem great - a regular meeting, a chance for staff to talk about things. But they're not. They're window dressing. If you need the 1:1 to see what mood your staff are in, you're not paying attention. If you need the meeting for your staff to be able to tell you what they could do with to make their work easier, you're not approachable.
From the perspective of a developer, they are an unwanted interruption, and a great example of the kind of make-work that gets in the way of productivity. You'll waste an hour in a 1:1, plus whatever time it takes to get back to what you were working on, and that is time that you usually can't spare.
I wish the managers earlier in my career had given me 1-1s. Done right, they can really accelerate your career development and help you get more out of your job, as well as be a better employee.
1-1s and being available/approachable are not mutually exclusive. Not every employee is comfortable bringing up nagging frustrations without a formal venue for them. Especially those earlier in their careers.
And in terms of interruptions, some of us would rather have an hour scheduled on the calendar that we can work around than random drive-by interruptions from a manager who wants to "stay in touch". A 1-1 is for those conversations that the employee might not otherwise initiate, and it's for exploratory chats that eventually make it to territory you might not have covered if you were only discussing what's front of mind.
A poor 1 to 1, performed because someone further up the chain has said they should be, can definitely be like that. You sit down, everyone says things they already know, and then you all walk away feeling like the time was wasted.
A good 1 to 1, with a manager who actually cares, can be fantastic. Until my last boss I'd written them off as a waste of time, but these days I'll actively seek them out. Good one to ones feel like a conversation, talking about how things are, what's working, what's not, maybe a heads up of potential projects with the aim of getting your input on them. When I left my last job I think my favourite one to one was the last one I did with my boss, I went in fully expecting it to just be "not much point in this", and ended up with a ton of advice on my new job, and how to best use my strengths in a different environment.
A truly great one to one does take a really good manager, and is helped along by a decent relationship with that manager, but you're doing yourself a disservice not to try and nurture that.
From the perspective of a developer, they are an unwanted interruption, and a great example of the kind of make-work that gets in the way of productivity. You'll waste an hour in a 1:1, plus whatever time it takes to get back to what you were working on, and that is time that you usually can't spare.