[事「こと」]だ => A is necessary/good (offering advice/suggestion) N3
Needs, Requirement
も[同然「どうぜん」]だ => The same as saying A, as good as A N2
Adjectival, Descriptions
[事「こと」]ができる => Be able to A; can do A, Can A; be possible to A; N4
Causative, Passive, Volitional
に[限「かぎ」]った[事「こと」]ではない => It's not limited to A, it's not only A N1
Degree/ Level/Amount