If you expect that the oven will have a lot of smoke from crud being burned off at high temp, keeping the oven locked during that period probably seems like a safety feature.
As for turning the oven on at a specified time: if you want to cook something on low heat for 6 hours, there's no way to make that dish on a workday for most people without such an oven. But with that feature, you can just time it to be done an hour after you expect to be home, and all is well.
If you expect that the oven will have a lot of smoke from crud being burned off at high temp, keeping the oven locked during that period probably seems like a safety feature.
As for turning the oven on at a specified time: if you want to cook something on low heat for 6 hours, there's no way to make that dish on a workday for most people without such an oven. But with that feature, you can just time it to be done an hour after you expect to be home, and all is well.