[pure-awesome]

"Apps like Instagram have a standard carousel for photo albums"

Yeah, but that only applies to users who are used to Instagram. It's definitely not an INTUITIVE feature.

I've had friends and family link me to Instagram posts, and though I've learned now, for a long time they'd have to explicitly mention there were additional pictures in the post, or I'd miss them.

(I don't know if it's different in the app, but certainly in the webpage those little dots at the bottom are non-obvious to a first-time user.)

[squiggleblaz]

I think it's more of a mobile-first design. It would be super weird to see it and do it with a mouse, but it's a common enough ui on mobile apps that I think a lot of people will be accustomed to it. But Instagram also has a feature where the second time you see a post that you haven't scrolled through, you see the second photo. This might server as a discoverability aid.

It is 153% the case that mobile user experience is almost entirely happened during the epoch when helping your user understand how to use the app rates second, and keeping some hidden features for expert users rates highly (the feeling of being a power user since you know some features others don't - making the user feel a little bit loyal to your app).

So if it's not perfectly discoverable, that's probable something the designers are happy with.

[gitgud]

True but that's just the first time experience, once they understand it, then user's will trust that the scrolling function will work on subsequent sessions.

With websites, every implementation is slightly different... so user's get that confusing "first time experience" every single new website they visit...