"MULTIHULL SAILORS DO IT ON THE LEVEL."
If a large bed and a level ride is required, the problem could be one of several;
1. Operator error
2. Lack of experience
3. No imagination
4. Fear of a "rough ride"
In defense of monohulls, here are a few pro's my boat had for that particular activity;
1. Plenty of handholds
2. V-berth ensures closeness for 2 people on either side. One side for each tack.
3. At anchor, with filler installed, v-berth has plenty of room for any position. The one on top gets to stick their head through the hatch.
4. Cushions on settee's can be repositioned for maximum fun or will cover the sole to eliminate risk of accidental "roll over".
5. Helmsman can see all the way to the V-berth for the "changing into my bikini" action.
6. A hammock strung between the mast and the forestay in a moonlit remote cove makes for all kinds of romance.
In conclusion, I refute the findings of the author of that article.