To understand why the various parameters are so important for Instagram, we need to take a closer look at the platform's business model. The video network earns its money through advertising and having many users look at it.
They attract users from all over the world. So for the one billion people to see the adverts from companies and influencers, the platform has to convince them with good and interesting content.
For this reason, Instagram is very interested in the platform suggesting to each user exactly the post and feeds that fit their interests and needs. Because only then will people spend a lot of time on the platform and see good ads from Influencers. So good engagement is inevitable for your growth.