Alice just e-mailed to say they her FI is upset that guests are buying items off their registry (and quite a large one at that). They put monetary gifts only on the invite.
I replied to Alice that older guests would prefer a physical gift to give, some guests may not like being told what to give and having a larger registry may be confusing to guests. What's done is done. I hope they graciously accept ANY gifts given.
They were hoping to re-coup some of the wedding costs through wedding gifts. If they don't, that's on them, not their guests