Lightroom or Ableton are almost impossible to run on a CORE-M. It's painful specially after a 10/15 minute editing session when the fans kick in and not only you have to deal with a noisy laptop but also your CPU gets underclocked and switching between your full screen Lightroom or Ableton back to Chrome sometimes takes more than 30 seconds.
WoW and LoL are very lightweight compared to pro image or sound editing software, specially because they are doing a lot of the heavy stuff in your GPU.
Even the Mac Pro is also kinda bad with that software to be honest, specially if you spend more than half an hour using it, because of the thermal issues.
You can both be right. Machine defects, or just aging, can cause the battery to expand and internals to coat with dust - causing thermal throtting, excessive fan usage, and significantly worst performance, after even just a year or so.
No, it wasn’t. I used to ru Xcode, iOS Simulator, World of Warcraft, League of Legends on the fanless MacBook with 8 GB of RAM just fine enough.