Yes, there are many disadvantages to remote work.
* Can't have lunch with coworkers. Lunch has always been a good time for socializing about non-work events and developing camaraderie.
* Can't go out drinking after work with coworkers, same benefits.
* It takes much more time to personally prepare one's own lunch than taking advantage of free healthy food now offered as standard benefit at campus by most reputable tech companies like Google.
* No employer provided on-campus child care.
* No employer provided Friday massages.
* When you don't feel like working, can't chit chat discretely about TV and sports with workers for several hours.
* Less mentorship capabilities for senior experienced engineers to be paired to train and guide freshmen. However, I haven't seen this in many companies so it's not going to be missed most places.
It's always been an advantage to work remotely if you are doing stuff where you are a sole worker who is able to work on black box projects where you get a spec or desire in and return a finished product. This works best for people that are recognized experts and is a subset of work possibilities.
The real sticking issue has always been retaining the advantages of highly collaborative group and team work. Being able to talk face to face, have all hands meetings, have access to the company source control server, be able to work on something in the same room with someone working collaboratively at the whiteboard and in a text editor. Ten years ago this was completely impractical as the infrastructure was just not in place.
All of that has changed rapidly in the last decade as tech and services have ramped up and delivered in spades. Not only is work able to be done electronically, but it is regularly being done electronically, and it works every bit as well as face to face, often even better since you have more control over distractions.
It's not only super advanced high tech companies taking advantage of technologies like video conferencing either. It's not leading edge at all anymore. Video conferencing comes built in to the ordinary inexpensive cell phones regular people have, and people with absolutely no technical ability are using it every day. It's an ordinary part of contemporary life. It is so common to do now, the idea that companies aren't doing it already or are fearful of it is quixotic and surprising that there are hold outs who are so backwards. It's like hearing about someone from the 1950s who came out of a stasis pod or emerged from a bomb shelter who isn't aware that cell phones and laptops exist. The suggestion that some of these companies are claiming to be startup high tech companies is almost completely absurd and unbelievable. You have to wonder what sort of investors are so clueless they would invest in management of a tech company of all things that simply doesn't know what it is doing and seems oblivious or hostile to the realities of the modern world.