Actually, Yan Qing was quite a simple Prince in terms of his background and environment, in all aspects.
Because leaning on a big tree for shade is a great help, with an excellent elder brother above him to take the lead, the expectations for him weren't that high, as he was being nurtured as an assistant.
Moreover, Yan Qing himself had little desire for politics, which led to a relaxed situation where even if he never attended the court, he wouldn't be impeached.
For the Crown Prince, it wasn't important whether his brother attended court or not; as long as he was happy every day, he fulfilled his responsibility as the elder brother.
For Yan Qing, staying away from politics was the best choice; even though his elder brother was kind to him, in the face of sensitive political issues, he had to choose comfort.
Even if he wasn't inferior to the elder brother, he had to act as if he were much less capable because that was the way the Imperial Family survived.