I would like to know the situations OP has experienced, but I guess they're gone already.

I have personally never seen anyone being rude to a healer who doesn't DPS. I myself am a person who will bring it up, though, if I see a healer would clearly have a chance for it but doesn't. Usually one of the two things will happen (these are real examples from the past few weeks):

<Me> Hey WHM, don't be afraid to do some Holy! ^^
<WHM> Ok ^^
>>> WHM proceedes to use some Holy, in the end of the run I thank everyone for the great run and the WHM receives 3 commendations (I queued with 2 friends).

<Me> Hey healer, don't be afraid to do some DPS when no one is in any danger! ^^
<Healer> Are you telling me how to play my job? YOU BETTER NOT BE TELLING ME HOW TO PLAY MY JOB?!?!
>>> Healer starts acting rudely and being defensive (although in this particular case, after I explained to them about my own healer experience in this game and how to use some DPS abilities easily, they did start doing some DPS in the end )

Some players, in the position of the healer, would read that second situation as "being harassed", especially if they have first answered rudely / defensively and then other party members have also responded with a harsher tone.

I'm 100% against any harassment and rudeness towards our fellow players, and will always try to step up and talk against it and report the player acting like that. However, from experience I also know that some people have difficulties making a difference between constructive feedback and harassment, so it's hard to judge situations without seeing the logs. In any case, it sucks feeling like you're being bullied when you just want to enjoy a new game you've only recently started.