In the phrase a user-friendly website, few would argue against the hyphen. It clarifies. You could get away with a user friendly website, because user friendly is a familiar term and there is little chance of ambiguity (though hyphen devotees may call you a monster anyway). But the hyphen is conventional.
Things get more complex when the phrasal adjective gets more complex. It’s a non-profit-making group, with two hyphens, not a non-profit making group or a non profit-making group or a non profit making group – though many writers are strangely suspicious of multiple hyphenation.
But one rule does not fit all compounds. When a prefix such as non- or un- is added to an item that may already be hyphenated, things get erratic, as I detail in a post on non-life-threatening unselfconscious hyphens. Take hyphens seriously, one stylebook editor wrote, and ‘you will surely go mad’.
A further complication: In some semantic niches, we have yet to settle on a default phrase, so there are variants, variously hyphenated, competing for popularity and status – though we can get a sense of emerging preferences from corpus data, as I show below.
What, for instance, is the opposite of a user-friendly website? I’m not interested here in synonyms like awkward, difficult, or unintuitive – only in compound modifiers based on negating user-friendly.
Fill in the blank: It’s a/an _______ website.