Yep since the first party app's primary goal is to generate revenue (over actually providing a good user experience), it's packed full of everything to achieve revenue generation:

• Ads
• Tons of tracking to figure out how long you viewed something, what you clicked on, and so on to build an advertising profile that can be sold
• Obtrusive Ads
• Lots of suggested/recommended stuff to get you to keep your eyeballs on the app longer
• Ads masquerading as real submissions
• Paid promotions

Third party apps don't have revenue generation as their sole highest priority (if at all), so naturally they strip out all of that stuff which makes for a terrible user experience.