Because users get confused are now have trapped transactions. Zero confirmation is not bitcoin, bitcoin is not about promises, it's about assurances.
Discussion
Users which have trapped transactions will have the trapped if they dont learn what is rbf and cpfp... i do not understand this pushing. It totaly just decrrases value instead of adding value for bitcoin. Bitcoin is about assurances and at the same time it is about responsibilities. Let people be responsible, do not put cushions around them.