For example, bitcoin is a cheaper alternative to debit- and creditcards as merchants have to pay less interchange fees.
This is only true if the merchant accepting crypto is either keeping it as crypto, or trading it to fiat manually. If they are using a service like BitPay, which will allow them to accept crypto but instead be paid in fiat, there is a 1% charge which is pretty comparable/only marginally cheaper than most credit card transaction fees.
Therefore we should contribute as a community by helping merchants to implement this system in their store.
Agreed. I often hear people lamenting the fact that bitcoin adoption isn't more widespread, whilst simultaneously doing nothing about it and not trying to spend their bitcoin. Speak to your local grocer, coffee shop, corner shop, tradesman, whoever and ask them to accept crypto. If they don't know there is a demand, then they have no incentive to start using it.