when painting is your livelihood and your end results cause additional jobs and your project shows professionalism, you will only go to paint dealers.
I like the hands on tech advice and assist on difficult surfaces. I know the end result of their paint. They will come to your site if you are encountering a problem. they do give you discounts based on your business you bring to the table.
I would never use any paint from a home center on any job that I am being paid for. I know the problems I will encure.
For a homeowner who paints their home and wants to spend less, then that is their option and I respect that.
There is a huge difference and any pro painter will know that up front. Price per gallon in paint is directly equated with quality and performance. Same with brushes and rollers.