This discussion could be held about ANY language. There are more than 7000 spoken languages in the world, of which many have several variations on the 'standard' form. The variation you speak depends on your social background or education, your profession or field of study. Theoretically it is possible you speak different variations at a different time and place; at home, at work, at your hobby club or when you apply for a job.
Language is a living phenomenon that ultimately is defined by the spoken word. If enough people constantly say 'were' in stead of the standard 'was' it will eventually become the standard. Purism doesn't work with language because it changes all the time, together with all the variations that exists and endure, like ripples in a pond.
This doesn't interfere with the sharing of reasoned thought. True, almost no one understands Legalese, even though (or so I assume) it is formulated in standard English. But communication - even more so between different groups - has always been difficult. It is simply a matter of finding the common variation.