Probably the vast majority of WordPress plugins, including Weaver Show Sliders and Weaver Show Posts, are updated on a different cycle than WordPress. It is not always easy or efficient to update every plugin every time WP updates – especially for sub-sub-versions (like 4.2.2). For one thing, it causes an unnecessary update of the plugin – which when multiplied by all the different plugins represents a lot of unnecessary bandwidth and effort on the part of everyone.
And, for actively supported plugins (for sure, any updated within 6 months or a year), updates to WordPress almost never cause compatibility issues with existing themes and plugins – like 99.9% of the time. (In reality, it is very likely that even plugins that haven’t been updated for several years will still work fine. WordPress is notoriously good at backward compatibility.)
So our policy is, in general, to not issue plugin updates unless there is a good reason to, and keeping up with the WP version is not necessarily a good reason. And we never update to sub-sub-versions – at most, we will specify 4.2, but never 4.2.3 or similar. The sub-sub-updates are always small fixes that never break themes or plugins.