Any truth? Yes. Anything actually interesting or meaningful that you need to worry about? No.
If you pour full strength bleach directly onto the liner, instead of into the water, you could potentially bleach the liner. But if you add it the way we recommend, by pouring slowly in front of a return jet while the pump is running it is nearly impossible to cause any damage.
More importantly, this is true of all sources of chlorine, not just bleach. There are many sources of chlorine, including bleach, trichlor tablets, SWGs, etc. All of them have exactly the same effect as far as "bleaching" the pool goes. Sitting a damp trichlor tablet on the liner will actually cause more damage than bleach, since trichlor has chlorine and also is quite acidic, and acid is slightly more likely to cause damage than chlorine.
[Different way of saying what JohnT already said.]