Why is saying "بارك الله فيك" (May Allah bless you) not considered an innovation (bid‘ah) after every question or piece of advice, even though it is considered a form of dedication (takhṣīṣ)?

The phrase "بارك الله فيك" (May Allah bless you) is considered a supplication permissible at all times, and it is not an innovation (bid'ah). Rather, it is a form of kindness towards a Muslim. The predecessors (Salaf) practiced this, as narrated from Ibn 'Awn and 'Ata' ibn al-Sa'ib, and they used to respond to such supplications in kind. 'A'isha, may Allah be pleased with her, commanded that a supplication be reciprocated when charity is given.