[rdl]

My understanding, which may be incorrect:

The "anonymity set" of a monero transaction is just the number of fake values created in it. This is a fairly small number. If you're willing to put the effort in, you can trace all of them.

For MW, the the anonymity set is either "all users of system" (if you don't believe in a global network observer) or "all users of system who exchanged parameters in a given set".

[AndrewBissell]

In addition to this, Monero has the same "linearly growing blockchain history" scaling problem that bitcoin does. fluffypony has floated the idea of a mimblewimble sidechain for Monero.