Thus, keeping up with this convention makes developer life easier.
Tabs carry more semantic information than spaces. Case in point: Converting from tabs to spaces is easy but going back the other way is hard (information is lost).
tabs can leads to badly formatted code if different people have different conventions.
auto Var = 0u auto LongVar = 1u
this looks 'better' as: (vertically align same col)
auto Var..........= 0u auto LongVar..= 1u
Replacing spaces with tabs here would break the nice vertical look.
If the people you code with are used to spaces your arguing about spaces is counter-productive to your programming.
It is impossible to layout code in a precise manner using only tabs. Spaces are required in almost every coding style, and mixing them with tabs can be confusing and lead to bad layouts.