Although a user can still see the Internet using an old browser, all browser suppliers, including Internet Explorer, Google Chrome, Safari etc all provide the option of upgrading FREE to their latest versions. They do this not only to improve the browser experience for the user, but also because each new version irons out security problems.
Furthermore, when it comes to editing a website or using any "modern" features in a browser, the people that create the software and editing tools can't be expected to design software that still works with unsupported browsers or software - things would never progress. If you are not able to edit the site fully, it's not because there is a problem with the site, but because there is a problem with what you are using to edit it!
We assume that all our clients are using up to date technology - it doesn't have to be the latest version, but it can't be so out of date that it is "unsupported". Otherwise, where would we draw the line? We couldn't still be supporting a platform for users that still used a 1990's circa computer and browser could we?
We also have to assume that if you are using a computer for your day to day business use, you either know how to keep it up to date and to upgrade it as and when required yourself, or you have access to an IT support firm that handle these type of things for you.