Initially IG was all hipster photos; remember when the arty filters were their primary USP? I remember using it as a kind of second Facebook, where the people I followed were all FB friends and we only posted photos instead of text posts and status updates.

I don't think it was until 2015 or so that it started getting huge in terms of user base size, and that's when the deluge of low-grade comedy, "IG Models", awful memes, spammers etc. descended upon the site, changing its culture to what we see now.