I'd still prefer a separate server even if it's only for myself:
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power efficiency, you don't need to keep a power-hungry PC on when you don't need it, but only an old laptop or a rasp Pi or whatever
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if your PC is down - broken, needs reinstall, having an issue that needs troubleshooting - you can still have your server stuff running
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expandability. Media server alone is good to stream movies to a TV, or to a phone over the web, and again the PC can be off