In my high school, the librarian didn't insist on silence; she insisted on grace and decorum. Which is a pretty big ask for teenagers. For starters, they'd have to look it up in a dictionary. We didn't have the internet back then.
Grace and decorum. Some might interpret that as being the epitome of courteous, elegant good-will and propriety that is fitting to the setting of the library. And sometimes, that would certainly mean silence - like, if we were expected to sit and read without interruption. Other times, discussion and learning necessitated noise, and that was also acceptable, so long as it was respectful and productive noise.
But when it came down to it, our school librarian was also a formidable no-bullshit kind of woman. On top of teaching us all how to navigate the library's collections, and cultivate fantastic reading programs, she was a champion against bullying, sticking up for the little guy, and had no hesitation in kicking out anybody who even started acting up in the library. In this way, an understanding of grace and decorum could be summed up by Wheaton's Law: Don't be a dick.
Like many librarians, I cut my teeth through the trial-by-fire rite of passage that is the public library service. By the time I was working there, we had done away with arcane rules of "silence" and patrons were even able to bring drinks into the library, which was deemed far considering that they were just going to borrow the books and read them over a cup of tea at home anyway. And although, silence wasn't enforced, the space was often very quiet, mostly with the regulars who'd come in and read the newspapers in their usual couch, or use the public access computers for hours.
The complaints would only really happen when the children's programs occurred... "This is a library, and they're making so much noise, singing and running around!" That phrase, "this is a library", indicating a holy place of silence, the sanctity of which the children's library had violated. Grace and decorum - children should be seen, and not heard. We politely addressed such complaints with the information that the library runs children's programs at these hours, and that perhaps they might prefer to visit the library at a different time.
Then there was the time that I was running sessions for the English Conversation Club. I'd set up a discrete corner of the library with a little coffee table, and there would be a small gathering of people from the community who were usually non-native English speakers, and spend an hour mostly just having a chat, with occasional explanations of the more idiosyncratic aspects of the English language.
It was at this time that I received the most vehement - and somewhat personal - complaint. "This is a library, and I can't read my newspaper when it's sounding like a Chinese laundry." He practically spat out the words. It seemed so nonsensical - I mean what the hell was a Chinese laundry? But the imagery was direct - invoking that of a horde of immigrants, creating cacophony and chaos, and destroying their civilised order and silence. In his eyes, we were the antithesis of grace and decorum. In my eyes, he was being a dick.
However, the library is for everybody, and we were soon able to move into a separate meeting room, where nobody would be disturbed.
I've worked in libraries for quite a while since then, and every time the issue of silence has come up, it's been at the instigation of the library user, as a result of another library user either engaging actively with computers, with each other, or seeking assistance from me. This is particularly the case, when assisting elderly people who are hard of hearing and need patient help using the internet, and as government services become more automated and online, it's going to be a growing demand in libraries that have online computer access. Every time somebody complains, that phrase "This is a library" is uttered, and each time, I have responded with, "We're here to help everybody who asks for it."
And the fact is that, generally speaking, you need to make noise to ask for help. It's the silent ones who are privileged enough not to need help, as they already have the skills and knowledge to be able to use the library unassisted. They don't need to be told that they're welcome in the library - they already expect it.
It's everybody else that we need to make noise with - to speak to, engage with, sing to, share stories and listen to. In that sense, grace and decorum means having the goodwill to welcome everybody into the space, and connecting with them in a meaningful way that allows them to succeed in whatever their needs are that have motivated them to visit the library. These people, who need the library - rather than those who demand the library, and silence - have just as as much right to be in the library space, using its collections. And anybody who thinks that these people don't belong is probably being a dick.