The push-to-left doesn't matter. Most people will read one thing on the site so they're not navigating between pages anyway, most of the remainder aren't clicking through pages fast enough to even notice the jump, most of those that do notice it know how scrollbars work, and the remainder is you :)

I guarantee nobody will complain about the jump, but they will (did) complain about disabling basic browser functionality.

If the jump really bothers you, you can replace your rule with

    html {
        overflow-y: scroll
    }

which should force scrollbars to appear on every page whether they're needed or not. But you don't need it.