Advice on creating such visuals

Hi everyone,

So today i got scrutinised and told off at work because I made use of calculation groups in my report.
I spent my whole weekend learning calculation groups and applying it to my work and the following users parry2k , kushanNa , amitchandak  helped me tremendously I can't thank them enough.
 
My team are not familair with calculation groups and their point was how will they support the reports when I am on holiday.

I never had the need to use calculation groups but I was tasked with migrating an excel report into power bi and some of the tables in the excel report were like below where you can see there are more than 1 level in the column header section (i.e. multi-tier column headers).

I was very disappointed and upset for being criticised for work that I invested a lot of my weekend time in trying to learn Calculation Groups to tackle the above visuals. 

I was told these visuals can be created without the need for calculation groups or measures by just creating a summarised tables with one column containing the names of the fields. I am not sure how this works and still don't know how it will be possible to create such visuals without using Calculation Groups. 

Now I have to do a presentation at work to rationalise why we should employ Calculation Groups and fight my case for taking the approach I have for this report.

Keen to hear from the wider community of their thoughts on this as I would like to know. 
Any comments appreciated it. 

Thank You!