If blackouts are very rare, over-prepardness is an inefficient deployment of financial resources.
If blackouts are very common, it's just sensible planning.
2. How widespread is a typical blackout?
If it's just a small area then during a blackout maybe you can mitigate it by leaving that area. If it's common across a broad area (e.g. the load-shedding in South Africa) learning where is and isn't affected is important.
2. How vulnerable are you to loss of electricity?
If you have a medical condition that requires electricity to mitigate then you should take steps to ensure that you can handle a blackout.
If you exclusively work from home and require electricity to do so then you should take some measures to mitigate it. Maybe this is identifying places you can work from in the event of a black out. Maybe it's a UPS for devices you need.
Most people... the downside risk is loss of power to fridges and entertainment devices.
Stockpiling a couple of days food is sensible. Stock pilling weeks means changing your meal plans to ensure you consistently eat long-expiring food and replenishing it, which may change your diet.
Power blackout or information blackout?
For power: inverters, batteries, solar, propane generators.
For information: phone modems to get around BGP route injections though truth be told I would just treat that as a vacation from the internet, HF/VHF/UHF radios for local chatter is all I would really care about.
However, I do have a power station and a couple of solar panels. If needed, I can reduce my power usage enough to operate indefinitely if necessary.