At the urging of Jobst Brandt, author of The Bicycle Wheel, Avocet marketed smooth-tread tires in the 1990s. Initially some cyclists thought they posed a hazard because they were “slick.”
However, Avocet knew better and had the test results to prove superior traction on dry and wet roads. After a time Avocet tires caught on, despite some difficulties in buying from the company. When Avocet went out of business, so went the tires.
Some tire companies have adjusted their product line to include smooth-pattern tires, but still include pattern tread in other models, including Continental. Michelin tires are pretty much all smooth and Bontrager sells smooth and pattern tread. These patterns do absolutely no good in rain. Hydroplaning is something car tires experience, not bike tires. Bike road tires have about an inch of contact and cannot trap water.
One tire I saw recently has deep patterns, which attract small rocks and glass shards. While smooth tires will pick up grit and glass too, a deep pattern encourages this undesirable event.