A shallow interaction is unlikely to lead to something deeper but occasionally things line up and it becomes the start of a beautiful friendship. That's equally true on social media or AFK.
Maybe introducing yourself in-person is slightly deeper than thumbs-upping someone's video, but by the same token the latter is a smaller step; you can always go with a full-sentence comment or a video response of your own if you want the slightly deeper interaction.
Shallow interactions are shallow, deep interactions are deep, equally shallow interactions are equally shallow whether online or offline and the same for equally deep interactions. I'm not going to argue about what specific action corresponds to the precise depth of pushing like, whether it's saying "hi", grunting, making eye contact, or what have you; both online and offline you have a spectrum of ways to interact and having both shallow and deep options available is important, because you wouldn't want to start at the deep end with a stranger; you start with something shallow and most of the time it stays shallow but occasionally you find it worthwhile to turn it into something deeper.
In public shallow interactions don’t need to stay that way. It’s not a question of the possibility of levels of interaction but the rates.
Many people can go to a bar and fairly reliably get laid several times a month. That’s simply not possible for the overwhelming majority of people using TikTok. TikTok / Twitter/ Instagram etc are designed to be shallow interaction so people stick around. Dating apps fill that niche, but also want people to come back.
Being in public allows for the full range of relationships in any setting. You can meet a great friends at a bar etc.
This argument doesn't hold on a pure numbers basis. If you are one of 10 people to make eyes contact with someone at the bar, you are already in a far more privileged position than being the person who added one of a million likes to a video.
In forms of social media that existed primarily to produce inter-personal connections (i.e. very early Facebook, or maybe even LinkedIn) your argument works significantly better, but the way that instagram/tiktok/etc prioritise influencers in your feed makes the likelihood of 1-to-1 interactions infinitesimally low (unless you yourself are also playing the influencer game)
Maybe introducing yourself in-person is slightly deeper than thumbs-upping someone's video, but by the same token the latter is a smaller step; you can always go with a full-sentence comment or a video response of your own if you want the slightly deeper interaction.