(Old Kind of Miracles Made Obsolete)
What stopped us from sending the miracles is that the previous generations have rejected them. For example, we showed Thamoud the camel, a profound (miracle), but they transgressed against it. We sent the miracles only to instill reverence.
وَما مَنَعَنا أَن نُرسِلَ بِالـٔايٰتِ إِلّا أَن كَذَّبَ بِهَا الأَوَّلونَ وَءاتَينا ثَمودَ النّاقَةَ مُبصِرَةً فَظَلَموا بِها وَما نُرسِلُ بِالـٔايٰتِ إِلّا تَخويفًا
wa maa mana’anaaa an nursila bil aayaati illaaa an kazzaba bihal awwaloon; wa aatainaa Samoodan naaqata mubsiratan fazalamoo bihaa; wa maa nursilu bil aayaati illaa takhweefaa