There are many different ways to keep your bitcoin safe. We have the hardware wallets, cold storage, and multi-sig. While software wallet is good there is a strong caution given against leaving funds on software wallets on phones or computers due to security vulnerabilities. Hardware wallets are recommended as the only secure option for self-custody.
I disagree that hardware wallets are the only secure wallet for set custody as you have said. Hardware wallets are just cold storage because they are setup not to get in touch with the internet only and to safely transfer bitcoin. The software wallets you mentioned if setup properly can still do just the same work. It is to be used on a device that has never came online and will never come online (airgapped device). And just like hardware wallets you transfer your funds and monitor the incoming transactions using watch only wallet on another device that is connected to the internet. This watch only wallet create the unsigned transaction and then send it to the offline wallet which is then signed there and return back again and then the transaction is broadcasted.
There are people that even trust this self created airgapped wallet than hardware wallets because some hardware wallets sometimes changes policy in future that could affect the back up of the wallet keys or seeds, example is the new ledger wallet policies. The only problem with this airgapped wallet is it requires someone experienced or tech savvy to actually set it up, a newbie can easily make mistake and therefor should just go for hardware wallets