Seen that go well wrong.
The developers started doing joins on the views. The views were multi table joins with user defined functions and all sorts of other fun stuff.
A lot of developers don't know near enough about database design and implementation to tune for operational requirements. A lot of DBA's go down the purist route and and up with a design that the devlopers can;t really use...

You can compromise a design for editing and reporting, you can't optimise it though. Use different databases.
So the real issue is does the performance loss or the integrity loss add up to the cost of maintaining an other database. if it doesn't then end up with a practical mish-mash of conflicting requirements.