The "use vinegar/use salt" dictum came about in the 'old days' when fabric dyes were often home done. The choice of which item to use, salt or vinegar, depended on the mordant with which the dye was set. One worked on some things, the other worked on different things.
Since we have no way of knowing what type of chemical mordants are, or would be, used in today's dyes, using salt or vinegar in our washing hardly affects our fabrics at all as far as the dye is concerned.
So having Color Catchers on hand for most of us is as much a part of our quilting supply cupboard as a rotary cutter, seam ripper, or design wall.
Jan in VA