A basic service isn't worth much at all, especially at busy periods for ATC. The listening squawk is designed to make ATC aware that you are on frequency without increasing their workload even further but give them a "window" to call you if they see a problem.
The claim that no situational awareness can be gained without obtaining a basic service is incorrect. I always listen out on a new frequency for a couple of minutes before transmitting for a service. Doing so allows the start of the "big picture" to be built. It's very apparent that many pilots don't; it's by no means uncommon to hear a stressed sounding ATCO tell a pilot to "Standby, you're third in the queue!" or similar. At such times there is little point in asking for a service so you might as well be on a listening squawk in any case.