Being able to talk to people immediately is critical.
(I've been running a remote team for 5 years)
If your units of work are so badly partitioned that this is a requirement, remote or local is not really the problem.
Since these things are often necessary, you need to be able to have that happen in a remote environment.
I agree with you though on one important thing - issues of interruption have little to do with remote/local. I try to interrupt people as little as possible either way, but I don't want remote working to sacrifice on real time communication when necessary.
Screw you, even if I was sitting right next to you, you have no right to expect a response to your query in a minute. I will get to you when it's the appropriate moment in my workflow, otherwise I'm just running around like a headless chicken all day getting nothing done.
Working time is headphones on time. You do not distract me when my headphones are on.
We are not doctors in an operating room, you can wait 20 minutes. Hell, if I let you wait 20 minutes there's a 90% chance you'll solve the problem without me.
Acknowledging communication can also be: "I'll be with you in 20 minutes". That gives me the option to (in 95% percent of the cases) respond with "cool" and plan my own time accordingly, and in 5% of the cases to respond with "sorry, we really need to deal with this now, and here's why".
How fast you respond when someone tries to communicate with you has very little to do with remote/local. I love remote environments, they have huge upsides. Not being able to go to real time when necessary though is a major problem.
Secondly, if someone interrupts you during a highly focused session of coding, there is no way you would reach same session immediately after interruption.
Think of it as Inturruptability Quotient for every task. It can be roughly defined as ratio of time required to reach same state as before to the time required to finish the job. There are some tasks like writing documentation or editing a proposal, where you can reach similar state of mind as you were before interruption fairly quickly.
However for tasks like programming, designing a db or simply thinking abut a hard problem can take even hours to reach the same level. Inturruptability Quotient is sufficiently high here, maybe more than 1 sometimes. Do you even realize how much grave damage it does to productivity.
I would much rather devote a solid 20 minutes, even an hour, to you than half-arsedly devote 20 minutes spread out over 10 hours in one minute chunks.
Generally though, you can count on being able to talk to someone when you walk up to their station. When running a remote team, I want people to generally "be around". We work very closely together though, so maybe our needs are not a good example.