Why not! I'm not particularly familiar with Macbooks personally, but If it can run what you need it to run, then it's an absolutely fine use for one! I'd consider removing the battery and running without it for safety reasons, but I'm not certain if you can do that with Macbooks - and besides, a laptop with a battery installed could be considered a home server with a UPS :P

The only more specific advice I have is to stick to stuff 7th Generation or newer on the Intel side if you plan on a media center use case, since 7th Gen intel stuff is when they introduced x265 hardware accelerated decoding/encoding into the GPU found on those CPUs, which is a great help. I love repurposing EOL hardware for this kind of use case, since it's imo a better solution than buying yet more electronics, and it also saves something from the e-waste trash heap.