If just not knowing how a word you read is pronounced can make it so you are unable to participate in a conversation in a meaningful way when you have the capacity to do so, imagine the effects of all the other barriers people have.
First generation (both first gen college and/or those whose first language isn't the one used in class) and lower socio-economic status students experience this all the time. How often do teachers pronounce words and/or define them just so everyone is on the same page? How often do we model being "dumb" or "failing" so that students are comfortable too? And, I know that is also highly fraught for many teachers for multiple reasons, since some have the privilege of being able to be "dumb" without issue, and others do not because they are also already assumed to be "dumb."