Doubts about the Vedas. Why do the Vedas talk about Perumal indirectly? Why have they not talked about Perumal openly? Why has Perumal created several demi-gods and traditions and why has he made people follow them based on their knowledge? Why has he not declared that he alone is the Supreme Being and made everyone follow Sharanagati as the means?

Like how we safeguard a rare ruby, the true and subtle knowledge about Emperuman is precious. Hence the Vedas talk about it subtly or indirectly. This is so because this knowledge must be learned through a preceptor.
Emperuman creates many demi-gods as a divine pastime of his. Brahma Sutra says that these are Emperumans “lokAvat lIlA kaivalyam”; Bhagavan creates this universe playfully. These are a result of his playfulness. He conducts the world based on the karmic effect of every being. This is also a reason why Bhagavan has created demi-gods.
Some people like some other Devathas. Perumal with a good intension allowed them also to enjoy the benefit.