I suspect that Dunbar's number includes fictional characters and people you don't know in person but have many information about them (celebrities, politicians). In the past people also had a few examples in this category, for example Jesus, or the local king, but that is at least an order of magnitude less than all current movie characters, celebrities, and politicians people are familiar with. Also, watching someone on TV is a stronger stimulus than merely hearing or reading about them.

So it seems to me quite likely that modern media consume our "empathy points". (And the clickbait media make it even worse, because they burn all kinds of "giving-a-shit points" like a wildfire.)

A solution is spending time offline with other people (doing something else than watching media). Because people are not automatically strategic, someone has to organize an event and invite others. LW meetups, former classmates meeting at a cafe every Thursday, etc.