If shareholders are treated as outside creditors, there will be less to go around for other creditors, particularly if the shareholder loan is secured.
There is no communis opinio that one should provide shareholder loans with a less favourable treatment on a global level.
The issue of shareholder loans has divided different legal systems with Germany and England at opposite ends of the spectrum and Austria and the US somewhere in between.
This 2015 article surveying the treatment of shareholder loans across commercial jurisdictions, co-authored with R J de Weijs of the University of Amsterdam, is accessible here. Republished with kind permission of LexisNexis Butterworths.