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Security - The Chromebook has not seen security updates in some time. While much less of a problem than a Windows or Mac OS computer, this is still a risk which is greater over time. For this reason we do not recommend continuing to use these devices “as-is”.
Functionality - Most services which are available online are constantly evolving, from UI changes to major code overhauls on the server side. Since these Chromebooks are no longer updated, they will not keep up to the server side changes and regular functionality will stop working. There is no way to know when this will happen.