In my opinion, this is not a big issue at all. To put it into context, you may have not gone to any event at the firm, and still be able to get a VS at the firm. It certainly helps because the best way to know about the culture of a firm is by directly speaking to those who work there. However, the work and practices generally remain the same across most firms (and this is more important than culture when crafting a compelling application). This information is easily accessible online, via their LinkedIn announcements for example. Another thing is that you could have been to events at other firms, whether online or not, and still reference this by touching on similar trends in work/industries. They just want to see the effort you have put into learning more about the industry and your overall understanding of it, as well as how you connect it to your experiences/resolve to work there.