Yes and Yes. Depending on the job, speech can be the determining factor. I'm a software engineer and once I cleared all the selection rounds (both written and interviews) for a job. I had a final meeting with the founder of the company. I was stuttering a lot. I never got the offer letter. The guy didn't reply to any of my mails after the meeting. I'm pretty sure it's because of my stutter. I was over qualified for the job and I didn't say anything wrong in the meeting with him.