How is 堪 different from other auxiliary verbs?
堪
(1) endure; sustain; bear; stand
(2) may; can; capable of; fit for

'堪' in '对身体的危害堪比心脏病发作' is definition #(2)
'堪' usually combine with a single character verb like '称' or '作', as in '堪称'(may be called as/ fit to be called as) or '堪作' (may be/fit to be)

[堪 + single character verb] are more classical and literary terms

For two characters verbs like  '作为' , it is more common to use '足以'(enough to), as in '足以作为'(capable of being/ enough to be ) instead of  '堪作为'
('堪称为' is an exception, it is as common as '足以称为')

[足以 + two character verbs] are more modern and colloquial terms