Leaving a conference immediately after presenting a paper?
Is there an etiquette regarding this? Should someone accept a presentation on a conference if they won't be able to be present for the whole duration?
There aren’t really any universally agreed-upon rules for such things, but as a general rule:
If the conference organizers are paying any expenses for your attendance (such as travel or accommodation), it is considered good manners to be present for at least a good chunk of the conference other than your own talk.
If the organizers are not paying your expenses, I don’t think they have either a moral claim or much of an expectation that you do anything other than show up and deliver the talk they invited you to deliver.
If you are in doubt about what the organizers are expecting from you, it is perfectly acceptable to let them know about your constraints and ask them if it’s okay to accept the invitation even though you won’t be able to stay after your talk. If it bothers them, I‘m sure they will have no trouble telling you.
No one can force you to attend the whole conference, but usually the purpose of conferences is to spread new ideas, discuss them and make connections.
You can certainly accept the invitation, deliver your presentation and disappear soon afterward. It's certainly not unheard of. Your presentation might be useful to others anyway, but you will miss part of the purpose of going to conferences.
It's certainly not viewed as odd to leave a conference straight after your presentation, plenty of people do it if they are super busy. However you will unfortunately have to skip the value of hearing other presentations, feedback on your own work and of course networking.