The Sims 3 is supported on both Windows and OS X/macOS but the latter is shown as inferior to the former since the game uses Cider, has a 2 GB RAM limit, and won't work on newer Macs. EA hasn't bother updating The Sims 3 so the issues the game has have never been fixed. Mac users got hit hard with this even more than Windows users as the newer Macs won't play The Sims 3 period. This isn't the result of the OS but rather the graphics card. Since the 2013 Retina MacBook Pro, Apple included Intel Iris Graphics and Intel Iris Pro Graphics but the problem is The Sims 3 and The Sims Medieval have never been updated to support it and uniquely to OS X/macOS, the game tends to crash when using newer graphics. As a result, post Late 2013 MacBook Pros have been unable to run The Sims 3 while pre-2013 MacBook Pros are able to run the game. The iMac also suffers from this problem, pre-2015 iMacs (except for the 2.7 GHz model with Iris Pro) will run The Sims 3 but post-2015 models won't work with The Sims 3. Especially frustrating seeing as a majority of Mac Simmers play on the MacBook Pro, particularly the 13-inch model, and The Sims 3 Mac Discussions was often flooded by threads saying 'Help! My Mac won't run The Sims 3!' or 'I have a 13' MacBook Pro and The Sims 3 doesn't work. Help me!'. Also other problems are that The Sims 3 was broken with the release of Mac OS X Lion, and there's also a similar problem reported by @BluebellFlora that El Capitan and Sierra won't work with Late Night and/or Ambitions.
I'm surprised that TV Tropes hasn't listed this in Porting Disaster or any of The Sims' YMMV pages seeing the Mac version is loaded with problems. Both Windows and macOS also have issues such as long loading times especially since most Simmers have 1.67 and nearly all EPs/SPs making this obvious when compared to The Sims Medieval. Even worse, some features are useless without a fix; some towns such as Shang Simla (China), Bridgeport, and Isla Paradiso are impossible to play due to lag, sprinklers won't water plants on Planter Bowls and Soil Rugs, and Into the Future breaking Skill Opportunities with the Advanced Technology Skill.
The Sims 4 is probably the only useful The Sims game on Mac since The Sims 4 doesn't have the problems that The Sims 3 has. It doesn't help (for Windows users) that The Sims 3 is the only oldest game available since The Sims 2 is no longer sold digitally (outside of contacting EA for The Sims 2 UC). As time progresses, The Sims 3 will be impossible to play on newer Macs without using Boot Camp to install Windows, owning an older Mac (2012 MacBook Pro), or owning a Windows PC.
I doubt if EA even bothers caring about The Sims 3 so I'm guessing The Sims 3's issues, especially the Mac crash issue, will never be fixed. The Sims 3 may be crippled but with bug/world fixes, the game does get better. I know not everyone is able to play the game on Windows so is The Sims 3 still worth playing if you only have a Mac running OS X/macOS?