In progressive enhancement (PE) the strategy is deliberately reversed: a basic markup document is created, geared towards the lowest common denominator of browser software functionality, and then the designer adds in functionality or enhancements to the presentation and behavior of the page, using modern technologies such as Cascading Style Sheets, Scalable Vector Graphics (SVG), or JavaScript.

If you need maximum, lowest common denominator portability, use sh instead of Bash. If you need the increased capabilities that it provides, use Bash and use it fully