this is a flimsy argument I keep hearing office- enthusiasts grasp at. there're other variations to the random, impromptu conversation/not-meeting but they all share the argument that "one may accidentally contribute something to unofficial meetings".
how often does that happen? is overhearing and joining random conversations a business plan? is this such a common occurrence and the outcomes so beneficial and so pronounced that they balance out the very long list of demonstrable and concrete arguments against working from work, such as time lost in transit and CO2 emissions from the pollution of transit?
if something needs more planning and discussion, or reconsideration, then schedule a proper meeting.
even if it was only title and brief description, I say it's still a vastly better user experience to have a personally curated list of updates to websites you want to follow than manually going to a dozen homepages and dealing with the awful layouts and disorganization they inevitably have (in addition to ads), many of which don't even have the option of chronological view.