There's definitely a tendency to romanticise the early years. At one point, we had a threenager and a teenager at once, and when I expressed frustration with my 3 yo parents of teens were always quick to tell me that teens were harder, forgetting that we had one.
Teenage SD is/was a bit moody, sometimes slams a door, rolls her eyes a lot, has wild expectations of the rich and exciting lifestyle she believes will be handed to her, reacts with fury to any suggestion she might participate in cleaning up after herself, and is more interested in her phone that people actually in front of her. All quite frustrating (she also has many excellent qualities but those are the challenging ones).
She does not fling herself down in the aisle of a supermarket and refuse to move, scream for entire car journeys because she didn't get the toy she wanted, pee/poo herself from time to time for no particular reason, claim to be hungry every 30 second all afternoon but then refuse to even taste her dinner, routinely get up demanding breakfast at 4am, refuse to walk but also fight being in a pushchair and end up diving headfirst out of it, or get into a battle of wills about whether a tutu, one sock, and a pyjama top is appropriate to wear to the park in winter. THAT was hard, and I am very, very grateful that we've now passed that stage and have a sassy 5 yo.
I occasionally look at baby photos and feel nostalgic but then I look at pictures of SD at 7/8/9 and remember how actually lovely those years were and all the things we could do together, the full nights of sleep and occasional hours where she occupied herself, and look forward to DD shedding the last of her toddler phase.