Regarding bitcoin, the main problem is that a lot of people have large amounts of bitcoin horded from early days and they tend to be biased and start spamming forums about how great it is as it will make them very rich if the adoption increases. This is despite there being very major flaws with the system.

As someone that has actually tried to sell things with bitcoin, there are major flaws with it, and they will never be fixed because these problems are inherent to blockchains. And people trying to get rich quick keep spamming forums and HN with blockchain technology X Y Z without acknowledging these problems.

1. It is really annoying to buy. You need to go out of your way to link your bank account and passport/driver's license at any major exchange, and this takes days or even weeks. You cannot buy it instantly with a credit card or paypal unless you find a shady seller with bad rates. No one wants to sell bitcoin for something that could be chargebacked.

2. No chargebacks. Good for sellers but not for buyers. People might be able to live with this if it weren't for the other 2 major problems.

3. Payment takes forever. Waiting for the recommended amount of confirms will take at least an hour?

These problems are deal-breaking and can never be fixed when using blockchain technology.