Why does my sister think that it's so wrong to blow your husband?

So my husband and I have been married for 4 years we have a great sex life and love each other so much. The other day my older sister( who has been married for 8 years) was at my house along with my Bestfriend and we were talking about giving our husbands blow jobs. I never even gave a ******** before I got married, but I started and my husband loves it. My bsstfriend said the same thing. And my sister started saying things like " only a husband who doesn't respect his wife would let her do that". And she said that its "not natural to use sex toys with each other". My sister is really conservative but I don't think its that bad. I mean you have to keep your love life alive. And i like keeping my husband happy and he does the same thing for me. What do you guys think?