OK, you have a point there... But let me ask you this. Why is no one accepting BTC payments through the Lightning network? We have several companies (mostly IT shops) that accept payment in BTC, but none of them accepts payment through the LN. Why is that? Is it that hard to implement that?
I don't have the data to back this up, but in my opinion it's mostly simply because not that much people are using Lightning(even though Bitfinex already implemented bitcoin deposits and withdrawals through Lightning, but maybe they just want to be the first exchange to support LN).
As for the difficulty of implementing lightning on a website, regardless how difficult it might be(I really don't know, because I haven't tried implementing LN on a website), if people want it, they would find a way to implement it no matter how complicated.