Yes there are challenges with adoption. Limiting the transaction capacity will not help.
It is a very stupid argument. Saying that current block size is limiting adoption is like saying a place is not attractive to people because it's overcrowded...
If only 3 people can send a transaction per second, then how do you expect 50 people to send a transaction every second (this is roughly 2.5% of what Visa does)?
To be fair, if Visa just throttled its throughput to 3tps, people would be forced to pay a hell of a lot more per tx, all the spam Visa transactions would disappear in the Free Market, and Visa would become the new gold standard.