It's about technological advancement and its augmentation of the human condition (think social media, phones, and the internet). There are people who resist these changes, often mislabelled as 'luddites' (the Luddites of the 19th century specifically opposed automation for its threat to jobs, but were reprehensive of all technology as a part of that).
This meme is just taking those who berate Luddites to their ultimate conclusion, which is a hive mind where all personal autonomy is lost, and it could be argued they cease to exist as a distinct individual. The flesh part of it is merely a means of making it more grotesque.
The problem with that whole concept is that it is often criticized by going the other way, i.e. that everything old is better, when in reality neither everything new nor everything old is great and change has to be evaluated on a case-by-case basis.
IDK, the first thing that came to my mind was an SCP where everyone started mushing into other people and making giant blobs because the sun (?) went crazy.
Its the "what do you mean babies shouldn't be integrated into the nexus from birth" and the "99% don't regret integration" bits that make me suspicious. Also it being 4chan. It being about the internet also makes a lot of sense though and I hope that was the intent