Yes i fully agree about the importance of the sequential way, because not everybody has that Dzogchen capacity. That this is a valid opinion, that not everybody is fit for Dzogchen that is explained in the advice from Horti Chenpo' s master, Mugyung Karpo.
They both are great Dzogchen Masters in the ZZNG Dzogchen Lineage, and they knew the importance of the Theg pa rim dgu.
So some deny the importance of Sutra and Tantra but that is not the general view inside Bon and Nyingma.
20. Horti Chenpo by:
Lopon Tenzin Namdak Rinpoche.
Horti Chenpo was a very important Master in those days because he held all the lineages of the Nine Ways (Theg pa rim dgu) and was very learned in all of them. At first when his Master Mugyung Karpo began teaching him all the 9 Ways of Sutra, Tantra and Dzogchen, Horti Chenpo only wanted to learn Dzogchen, so he asked his Master for these Teachings alone.
But his Master replied, "If you hold the Dzogchen lineage alone, what will you do if your pupils need another Teaching? You have to help all beings according to their capacity, so then what will you do? It may be enough for you personally to practise only Dzogchen but you must study and practise all these Ways because we never know what will be useful for other beings in the future."
Horti Chenpo's teaching:
"The view is impartial. The meditation is not focused yet clear. The activities are fully integrated with the Nature, they flow non-stop and
unchecked. You don't need to expect the result, it will be received spontaneously. The view and result will appear spontaneously from the Nature. This is called the Activities of Dharmakaya."