Dental Crowns for Teeth That Are Too Dark for Veneers?

It is very common to do veneers on dark teeth. There are many techniques for masking out dark teeth, including opaque veneer material, blocking out tooth structure before veneers are placed, etc. It is likely that your dentist is not familiar with some of the methods or materials available. If this were MY situation, I would NOT be doing crowns, I would insist on veneers.  If your dentist says it won't work, seek a second opinion.
Dark teeth are one of the main reasons I place veneers, as do many others.

Placing crowns instead of veneers to mask darker teeth is not necessary.  A well trained dentist working in conjunction with a good lab should have no problems masking darker teeth with veneers without the unnecessary tooth removal for crowns.

Nope! your dentist don't  have it right ...Sorry

You can mask dark teeth with venneers very well if he or she uses a good dental laboratory 

The root canal tooth definitely needs a crown though

Will add some photos later

There are new materials on the market that can mask a dark tooth with a veneer, for example E-Max.  It is beautiful, strong and could mask the color better than other materials.  If possible be as conservative as you can.  Perhaps some of the teeth could be veneered and the extremely discolored ones crowned to mask the darkness.

I do it all the time and get great results. The key is to use a talented enough ceramist so you get a great result without the staining shining through.