The biggest benefit of using a clock, in my opinion, is a social benefit. The clock establishes an estimated playing time for the game. In the case of a clock with no increment, it establishes an upper limit of playing time for the game.
This time reservation can be communicated (negotiated?) with your spouse, family, etc as you balance the competing interests of your hobby and your social life.
I absolutely hate playing real-life over-the-board chess with a clock. For the longest time, literally centuries, there were no chess clocks and people, especially when playing casually, didn't have any clocks nor time limits. Yet, it seems that nowadays such a thing doesn't exist.
Playing chess without clocks seems to be such a non-existent thing that I wouldn't actually be surprised if there are huge amounts of new players who don't even know that you can play chess without clocks. I'm sure there are many, many people who honestly think that clocks are mandatory in chess, and a fundamental part of it, and that it's somehow against the rules to play without, or something.
The thing is, chess clocks, especially when using shorter time controls (15 minutes or less), completely destroy one of the richest potentials of real-life casual chess: The social aspect. Plus, they usually just destroy interesting games due to either time pressure or the game ending too soon, before it's actually finished.
I play in an MtG group, and there are no clocks in MtG. And that's just fine. Every player can take their time, without pressure. They can do whatever they want, at their own pace, and opponents can respond, at their own pace. And even if a player is taking a bit of time, the other players can socialize by having a nice conversation about something. Take your time, no time pressure, others can socialize. Yet games do progress and end sooner or later.
No such thing in chess. Go anywhere, like a chess club, or some bar where people are playing chess, or wherever, and suggest to someone if you could play without clocks, and they will look at you like you are insane. Seriously. It's like even the suggestion is something completely ridiculous. Even if it's not any sort of tournament or anything, just some casual chess, it appears that people just can't grasp the concept of playing without clocks.
Yet, the clock just destroys the game. It makes it impossible to have a casual conversation, it makes it impossible to socialize while playing a lighthearted casual game, and it destroys most games either via time pressure or by ending the game too soon.
Some time ago I went regularly to a local chess club, and I got so utterly tired of this that I started just ignoring the clock, not even looking at it, and just playing at my own pace (I did press the clock after making the move, but I didn't care what the clock was showing.) Quite soon I started losing every single game I played by time. All of them. In all the "tournaments" that were played in that club I would always bet 0 points because I would lose every single game by time. And I did that deliberately, as a kind of form of protest. I got so utterly tired of the clock that I didn't care. It was actually more fulfilling to take my time thinking about the positions than stress about the clock. "F the clock, I'm not letting it dictate my pace. If I lose on time, then so be it. F it, I'll lose every single game on time, willingly and purposefully."
I suggested many, many, many times playing without clocks. I didn't get to play a single game there without a clock. Not one. That's how "ridiculous" such a suggestion seems to be.
Sheesh. If it were up to me, chess clocks would all be destroyed. The entire concept removed from human consciousness.