That's what slack huddles and channels are for! Getting help, knowledge sharing, meetings and catch ups, can all be done successfully remotely. Does require a culture shift and a certain level of engagement in using those tools but it's not impossible, we've been doing really well with it and for longer term WFHers like me (10 years now!) it's much better because the 'office' is now in slack. It'd take some monumental offer to get me back in an office, even one day a week.
More modern practices (and I am joining one in a month's time that does sound more like what you describe) might be up on that but even with significant amounts of resources that we have available within our SharePoint they don't get utilised.
It is a chicken and the egg scenario - do you need the mentality and willingness to already be there before it is worth transitioning or do you need to spend the money on infrastructure and training first to give people the tools to do it and then start moving in that direction and getting people in the right frame of mind for it.
It comes back, for me, to people's comfort/willingness to reach out and ask questions (and there have been studies of late around "tech fear" from younger people where they don't want to admit to not knowing how to use something, due to the stereotype that young people all know how to use modern tech, where as people my age and upwards will more readily admit to not knowing things and seek out the assistance)
I think as well that people who go into my industry are less often that savvy to the likes of Slack etc so maybe awareness simply isn't there?
Personally I am an advocate for people being able to work from home but I do think you need to "earn" the trust to be able to do so more than you are in the office. I do think as well that seeing the team (and wider firm) in person and socialising here or there is good too though. Those of us who go into the office will tend to go for a pint or two after work or play 5 a side at least once a week and there is something nice about these people not just being other drones in the hive - that said I have very few friends in real life and no partner so they are the sum total of my social life...