Sthanakvasi generally avoid the Nishith Sutra because, in their tradition, it is not accepted as part of the core authorized Agamic corpus in the same way as the commonly accepted scriptures.

Main reasons:

1. Scriptural acceptance differs

- Sthanakvasi Śvetāmbars traditionally accept a limited set of Agamas. - Nishith Sutra is not included in that main accepted set for many Sthanakvasi traditions.

1. Concerns about later compilation

- Some Jain scholars and traditions consider Nishith Sutra to be later or less uniformly preserved compared with other Agamas. - Because of this, Sthanakvasi do not give it the same authority.

1. Its subject matter is mainly disciplinary

- Nishith Sutra deals with rules, faults, and expiations for ascetics. - Sthanakvasi lineages often prefer to focus on scriptures they regard as more central for daily study and conduct.

1. Traditional study practice

- In many Sthanakvasi communities, the emphasis is on the Agamas they have historically preserved and studied. - So Nishith Sutra is usually not recited or taught as a standard scripture.

In short: they avoid it mainly because of their scriptural canon and tradition of accepted Agamas, not because it is rejected by all Jains. Different Jain traditions may treat it differently.

If you want, I can also explain what Nishith Sutra contains or how Śvetāmbara, Sthanakvasi, and Terapanthi views differ.