Some time ago, I went for a architect role at a telco which was the largest Progress shop in the southern hemisphere. The interviewer asked if I knew Progress and I said "No but that is only knowledge" and talked about successful projects and later found out I was hired because of that sentence. But I knew 15 languages at the time so what's another language, and sure enough, 3 months later I was reviewing Progress code. You have to convince them to hire you because of your perceived value. I have interviewed a lot and it always cracks-me-up when I ask if they know some technical thing and the job-seeker goes "No, but I've heard of it" meaning they are unwilling to admit that they don't know one of the million of technical languages/platforms/etc. We aren't Leonardo daVinci, who was probably the last person on Earth to know pretty much everything. It's OK to say No. So say No and explain why that doesn't matter.
Regarding the tools we use, I agree again. I have used the same DBMS for 15 years. I know it, I feel safe using it, I know what it likes and dislikes. The majority of all my coding is in stored procedures in the DBMS and I don't really care what the front-end is, whether it's C or some new-fangled hot platform. The lower level your coding the better. Find something that works at a low level and stick with it.