spusuf

Security. Having your data in your own control instead of blindly trusting companies, where it's more likely than not your data is being sold.

Choice. If there isn't a feature, add it yourself, switch frameworks, change everything if you want, no more "we're working on it" status updates when something isn't working or a feature isn't out. All the options are in your hands.

Pricing. Why pay monthly for "premium features" when you can have the most premium tiers for free. Especially true on anything with storage limits, 1tb of storage drive being cheaper than a few months of 1gb storage on some apps.

Speed. Sometimes it's just more streamlined when there's less bloat and you've hosted the exact thing you need on your subdomain with a single login page between you and the exact page you need. Less interaction needed to get where you're trying to go.

A hobbyist servo motor and ESPHome. Nothing off the shelf at the moment

considering OP has said "old router" I feel like it's a budget constraint thing.