Yoga Rahasya Chapter One verse 31

sthūlaḥ kṛśas-tathā śuṣkaḥ vakraḥ paṅguḥ śarīrataḥ |
atas-teṣāṃ na sarvāṇi vihitānyāsanāni vai ‖

There are different body structures,
therefore not all Āsana are enjoined.

sthūla - gross, tangible, material; large, thick, stout, massive, bulky, big, hugeśarīra - any solid body; bodily frame; one's bodyataḥ - therefore, thus, consequently, hencena - no; not; nor, neithersarva - allvihita - destined or meant for; prescribed, decreed, enjoinedāsana - particular posture; sitting, sitting down; seat, place, stool; abiding, dwelling

Commentaries and Reflections

Paul Harvey:

“There are different body structures,
therefore not all Āsana are enjoined.”