The datetimepicker tag has two problems in my opinion. Firstly, the name of the tag is incorrect because datetimepicker is not a word. However, I can understand why this name was introduced, since some UI libraries have used some version of this as a proper noun. Given that the tag excerpt also uses Datetimepicker I'm assuming that this isn't simply a question of tag formatting. I propose that the name used should be date-time picker and following convention the tag should be renamed 'date-time-picker'.
Secondly, the tag is potentially too broad as it seems to cover date-time pickers, date pickers and time pickers. Date pickers and time pickers are separate controls which are not always used in tandem, while, a date-time picker is a combination of the two. Should this tag cover all these controls or should it be divided into multiple tags?