"Fixing" frontend form validations

Some form inputs apply pattern checks (e.g. on the telephone number).

An example: <input type="tel" name="field_mobil" class="phone form-control col-md-3" id="input-handy" value="" required="" size="20" pattern="[0-9]+">. This specific one made the form not accept my telephone number even though it was correct. Removing the pattern attribute using the WebInspector made the “validation” go away.

This is just to be expected, but still something that feels weird.