Few people have the time to sit and write a journal each day. I tried and it became a burden, a dread before bed time. Sleep won out.
Journals can also be electively subjective. Yes, a photo can be framed or posed, but it's harder to edit awkward truths out of a photo rather than omitting them from a journal.
I keep a journal. I write in it when there's something on my mind. I don't force myself to write in it every day, or at all, that would be ludicrous. Sometimes I write in it all of the time. Deep thoughts about life get indiscriminately mixed in with movie reviews, shopping lists and the fact that the name of the guy who unblocked the drains was Nigel. I write more than I read. Sometimes I search it for practical information (what was his name again?) which is why I keep it digital.
So if I really want to, I can find out how I was generally feeling in, say, 2006, and what sort of questions were on my mind and what ideas I had. Usually the answers are: pretty much the same, and stupid ones, kind of like today but worse. So it turns out that I don't want to review my journal much. But I only know that I don't want to because I have the option, so it has a reassuring function, and writing helps me think in the first place.
When it comes to photos, though, I'm with Ray Davies:
People used to be always ready to scrible down things in the past I think, perhaps in the same way people are eager to take pictures now. Ofcourse one can't know before hand what's worth noting down and what's not, so I guess they would have just scribbled down everything, like when Plato wrote down what Socrates said.
Journals can also be electively subjective. Yes, a photo can be framed or posed, but it's harder to edit awkward truths out of a photo rather than omitting them from a journal.