"FCMP fixes most of this"
Lightning is already ahead of monero on privacy tech. If they eventually get around to adding support for FCMP (next year? year after?) I look forward to find out if FCMP even does what it claims to do.
But even if it does, it will still be worse than lightning.
FCMP accomplishes a similar goal as lightning (make the payment info look like something *anyone* could have made -- LN does this by making it an indecipherable encrypted blob, FCMP does this via a much larger zero knowledge proof).
But FCMP's method is much less efficient way. Not just because it uses a far greater number of bytes, but also because every payment goes on the blockchain, and you have to *pay for* all of those bytes. It costs a far greater amount of money to use FCMP than it costs to use lightning, and for all that cost, the effect you get is roughly the same: people can't tell who sent the payment anymore.
Lightning is better than FCMP.