did anyone really say it's hard to build on monero? why would anyone lie about something like that? all darknet marketplaces take monero. those are ecommerce platforms that are built from scratch, without javascript mind you. almost none of these ecommerce platforms take bitcoin. and there are ZERO darknet marketplaces that take lightning.
the difficulty level in building a darknet marketplace and keeping it running without issue is about as high as possible, the risks are worse than you could imagine, and the administrators and developers still have a strong preference for monero while totally shunning lightning. you couldn't come up with a better real life test if you tried.