Why don’t AccountingForm, NumberForm and DecimalForm print more decimals?

I have the following set of equations:

xs = 9295050963679385441209; ys = 10721945986215692199666; x = xs - 10000; exponent = 0.666451549104308964``18; xs1gt = Power[xs,exponent]; 

Which should produce ~437295921404696.997750975489799605.

If I naively print xs1gt, I get this:

4.372959214046970*10^14 

I looked for solutions on StackExchange, and I found the How to avoid the scientific notation in output? thread. Unfortunately, none of the solutions proposed there worked:

AccountingForm[xs1gt, 33] DecimalForm[xs1gt, {15, 18}] N[xs1gt, 33] NumberForm[xs1gt, 33] NumberForm[xs1gt, 33, ExponentFunction->(Null&)] NumberForm[xs1gt, 33, ScientificNotationThreshold->{-Infinity, Infinity}] 

Outputs:

437295921404697.0 437295921404697.000000000000000000 4.372959214046970*10^14 4.372959214046970*10^14 437295921404697.0 437295921404697.0 

I searched high and low for alternatives, and I stumbled upon InputForm and SetPrecision, which finally gave me satisfactory results:

InputForm[xs1gt] SetPrecision[xs1gt, 33] 

Outputs:

4.372959214046969977509754897996045`16.295988813986288*10^14 4.37295921404696997750975489799605*^14  

Now my question is why didn’t the other approaches, i.e. AccountingForm, DecimalForm and NumberForm, produce a similar result with 33 significant figures of precision (15 digits and 18 decimals)? I am especially confused by DecimalForm not having worked the way I expected.