How can I make Safari or Chrome remember my messages in contact forms?

As you can check that Ben posted his answer on February 12, 2017, while the official Magento blog post was posted on May 30, 2017.

So you can trust on the official Magento blog post.

And since there is no such official announcement (18 months notice) yet for stopping the support for Magento 1.x, we can still use Magento 1.x for our current installations.