But don't worry about it.
First, rubber isn't generally used on the waste side of a dishwasher or washing machine. And the vinegar is only going to touch the waste side of the pipes.
Second, "The dose makes the poison" in all things. The vinegar you are using is very diluted. It's just not strong enough to hurt anything.
Why use vinegar at all? A slightly acidic solution can dissolve calcium deposits and a few similar salts. These are known as "hard water stains", and a weak acid can help remove them without damaging anything.
The kernel of truth is products like drain cleaner are strong alkaline solutions instead of strong acid solutions. Strong acid solutions would clear clogs a little better. But strong acid solutions can also eat cast iron pipes, which is what all drain lines used to be made of. If you used a strong acid, you had to take extreme care to sufficiently wash the acid out, or it would heavily corrode the pipes. So the people behind Draino and the like use a strong alkaline solution instead, because they can't trust consumers to wash the acid out properly.
People hear that kernel of truth, and extrapolate it to vinegar because it's also an acid. But vinegar is a much weaker acid, and you're using it at a very weak concentration.
To get a vinegar solution where you would have to start worrying about the seals and tubing, you'd have to go to a chemical supply house and get the 100% acetic acid they have. The "distilled vinegar" bottles in your grocery store are about 5% acetic acid. And then you dissolve a little of that into gallons of water in the washing machine/dishwasher.
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