Do new players miss out on certain things that vets got to experience?

[Odett]

You won't really miss much on the fights themselves, but rather the experience you have with the fights. Like back in 2.0, beating Titan HM for the first time and feeling accomplished as hell with your shiny new relic, or beating T5 without the echo, and T7 without the nerf, but that's really all there is. You still get to experience all these fights, you'll just have a different perception of them.

[Juneri]

You won't really miss much on the fights themselves, but rather the experience you have with the fights. Like back in 2.0, beating Titan HM for the first time and feeling accomplished as hell with your shiny new relic, or beating T5 without the echo, and T7 without the nerf, but that's really all there is. You still get to experience all these fights, you'll just have a different perception of them.

Exactly. You can still do the content, but it's just not quite the same. I'm sure T5 was hard when it came out, but it only took a couple sessions for me to get through, probably within a week or two of 50. This really hit home when I finally went back to do some of the older level 50 dungeons later on, e.g. Wanderer's Palace. The videos and guides made it seem decently challenging, and I'm sure it was hard indeed back in the day, but in practice we just burned through everything super quick due to the power creep since then.