I asked a very similar question a few years ago, which Arthur was kind enough to answer. Since then I have seen variations of this question on a number of occasions, which to me means it’s a good one! I wish I could find Arthur’s answer, because it would still apply here.
The gist of it was that blockchains are essentially tokenization engines. Holochain is not. This is a rather large difference.
Building a social network on blockchain? Well, it will be tokenized somehow, whether it’s necessary or not, whether it makes any sense or not. New, fast, efficient blockchain systems like Avalanche might be great for things that really need tokenization, like Defi for instance, but for myriad general purpose application design, which is arguably MUCH more interesting than just tokenizing everything, Holochain is the way to go. But also it can do currencies as well.