General questions
Why is a WhatsApp group not enough for event photos?
The short answer
A WhatsApp group works for a few photos, but it quickly becomes a stream of duplicates and messages, the photos get compressed, and guests struggle to find themselves.
At a big event, the group fills up with dozens of photos, screenshots, and jokes, and within a day you cannot find anything in it.
On top of that, WhatsApp lowers the quality of the photos, so even if you do find yourself, what you save is usually a compressed copy, not the full file.