My TRS-80 model 1 did not have enough memory (4K). Writing early BASIC programs like a program to maintain D&D character stats, I very quickly ran out of space. When I upgraded it to 16K it was adequate as far as RAM. Cassette storage reliability was another issue entirely - none of my old programs have survived.
My college roommate's 512K Mac was way too painful to copy files between floppies - you had to swap them at least a dozen times. It became difficult to manage files and back them up. My later Mac SE was a lot more usable once it had an internal drive.
My PowerBook Duo 230 was surprisingly adequate for writing and programming especially when I started using a magneto-optical drive to back things up.
My later PowerBook G4 was inadequate for audio stuff - I was trying to record podcasts and mix things. I had endless trouble getting a clean recording with an extern USB microphone or headset and mixing audio really strained my hard drive space.
Wi-fi bandwidth was not adequate for what I was trying to do, about 2006 through 2012 or so - I was not able to serve my iTunes library to a different machine across Wi-Fi, and have that different machine stream the audio to an AirPort Express to listen to, without breaking up or stuttering. It's still tricky to get this to work even with much faster Wi-Fi with a 7th generation iPod Touch, although it works great with a recent iPad.
A very old Intel Mac Mini was not really adequate for recording and mixing my podcast projects although it worked better than the the G4.
My 2008 Mac Pro was great for all my video and audio projects with added RAM and 4 internal drives. It's still my workhorse machine for my big e-mail archive and producing podcasts.
I am using several little Intel NUC machines, i3 and i5. They are surprisingly fast. I use one as a headless build server for personal projects using VSCode. My kids use a couple of them for gaming even though they have pretty minimal GPUs. But they work just fine for a lot of games, especially games that are a few years older.
My M2 MacBook Air is shockingly powerful enough for anything that doesn't require a huge amount of storage, so it's my new workhorse for writing, programming, Logic Pro mixes, etc. I can even generate Stable Diffusion images on it. The big archive of projects lives on a Synology now. The battery life is finally long enough!
I'm planning at some point to replace the 2008 Mac Pro with a machine set up specifically for video projects. It might be a new Mac Mini...