I believe that computer picks up the frequent words very good and it is very useful and you save lots of time
Yes it is useful. It shows us the frequent words and in what context they are used, when reading long texts you may not recognize them but concordance helps us, for example I did not recognize the word adapt as a frequent word but concordance helped me!
Multi-conc helps students to identify whether a word is a noun, adjective or an adverb and in what contexts it is used. Special training would help students to use the tool better.