Do such companies need it?
Yes, maybe they need it to reach wider customers including residents of countries where fiat is not supported by digital payment services.
Is such an adoption going to harm the overall value of bitcoins if sales will take place through big companies (not Tesla and all who are here for profit)?
As you said, the point is for profit. However they will seriously think about the circulation of bitcoins received in order to maintain their value in fiat. After all, amazon vendors also have the option of whether they will trade immediately or hold it.
now your question is also my question , amazon accept BTC currently not seen officially on amazon in payment category , and they store BTC like a whale and can wait for the price to go up and sell it.
What are you talking about? amazon hasn't even officially accepted bitcoin yet