Because the website can't run in the background like an app, it can't preload anything. Launching takes a few moments to show posts, and videos don't autoplay.
Any time the mobile website shows you a prompt to use the app for "an improved experience", they really just mean "for better tracking and personalized ads".
I've been working on native mobile apps in the last couple of years, and I realized the only reason companies want to push native apps is because they can do whatever they want with the tracking and 3rd party stuff in general.
Seriously this native apps world is so backwards compared to the web...
I'll take youtube as an example, on the mobile web app you can block most ads and you don't get the latest stupid features youtube is trying to push for some reason. Sometimes I'm brought back to the native app through a link and I'm shocked. The only reason I keep it is Chromecast support.
YouTube Vanced (3rd party YouTube app) with its integrated sponsorblock actually makes the app pleasant to use, it also unlocks some of the premium only features like background play.
No root required, although you're buggered if you run iOS presumably
Best part of using it in a browser is that I can open links in new tabs. So I dont have that issue where going back to the homepage causes the feed to refresh.