ط، د، ت share an articulation point near the tongue tip and the roots of the upper front teeth. Their qualities differ, so they remain three distinct letters.
طَيِّب has emphatic ta.
دِين has dal.
تَابَ has ordinary ta.
A shared makhraj does not make these sounds interchangeable. Replacing ط with ت changes the actual letter, not merely its decorative quality.
Opening interactive controls...
Articulation of Letters — All Seventeen Makharij
ط، د، ت share an articulation point near the tongue tip and the roots of the upper front teeth. Their qualities differ, so they remain three distinct letters.
طَيِّب has emphatic ta.
دِين has dal.
تَابَ has ordinary ta.
A shared makhraj does not make these sounds interchangeable. Replacing ط with ت changes the actual letter, not merely its decorative quality.