Should cssselect be a dependency of this project?

[idgserpro]

I'm having the following traceback:

Traceback (most recent call last):
  File "/home/user/.buildout/eggs/plone.transformchain-1.2.2-py2.7.egg/plone/transformchain/transformer.py", line 50, in __call__
    newResult = handler.transformIterable(result, encoding)
  File "/home/user/.buildout/eggs/plone.protect-3.0.19-py2.7.egg/plone/protect/auto.py", line 162, in transformIterable
    return self.transform(result, encoding)
  File "/home/user/.buildout/eggs/plone.protect-3.0.19-py2.7.egg/plone/protect/auto.py", line 275, in transform
    for form in root.cssselect('form'):
  File "/home/user/.buildout/eggs/lxml-3.6.0-py2.7-linux-x86_64.egg/lxml/html/__init__.py", line 423, in cssselect
    from lxml.cssselect import CSSSelector
  File "/home/user/.buildout/eggs/lxml-3.6.0-py2.7-linux-x86_64.egg/lxml/cssselect.py", line 16, in <module>
    'cssselect does not seem to be installed. '
ImportError: cssselect does not seem to be installed. See http://packages.python.org/cssselect/

Putting cssselect in my eggs section solves the problem. Shouldn't it be a dependency for plone.protect?