Why "\newcommand{\bal}{\begin{align}} doesn't work?

Question

I have this string in my preamble:

\def\bala#1\eala{\begin{align*}#1\end{align*}}

and I tried to rewrite it as:

\def\bala{\begin{align*}}
\def\eala{\end{align*}}

or as:

\newcommand{\bala}{\begin{align*}}
\newcommand{\eala}{\end{align*}}

but I noticed that it doesn't work for the align ambient (starred or not). It works for others math ambients like eqnarray, equation etc.

This is a Minimal NOT working Example:

\documentclass[11pt]{article}
\usepackage{amsmath}

\newcommand{\bala}{\begin{align}}

\newcommand{\eala}{\end{align}}

\begin{document}
My aligned equations
\bala
1+1&=2\\
2+2&=4
\eala

\end{document}

But the next one works:

\documentclass[11pt]{article}
\usepackage{amsmath}

\newcommand{\bala}{\begin{eqnarray}}

\newcommand{\eala}{\end{eqnarray}}

\begin{document}
My aligned equations
\bala
1+1&=&2\\
2+2&=&4
\eala

\end{document}