That shouldn't really be necessary though. If electrum really works properly that is. But i guess anyone reading this thread will always do that from now on lol.
It is not about Electrum working properly or not, it is about the user writing the words on paper correctly. Doing everything from scratch to recover the wallet (eg. re-boot into cold storage OS, install Electrum, enter 12 words, etc.) makes sure they have done things correctly. It also has the benefit of actually trying to recover and learn how it should be done.