If the numbers are not going to be used as references in the text they serve no real purpose in the bibliography and are useless and superfluous.
In fact I would argue that the numbers can make it harder to navigate the bibliography because take away attention from the important bits of the entry, namely the author name and year.
Compare
\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}
\usepackage[style=authoryear, backend=biber]{biblatex}
\DeclareNameAlias{sortname}{family-given}
\defbibenvironment{bibliography}
{\begin{enumerate}}
{\end{enumerate}}
{\item}
\addbibresource{biblatex-examples.bib}
\begin{document}
\cite{sigfridsson,worman,nussbaum,geer}
\printbibliography
\end{document}

(as found in Biblatex enumerating sorted bibliography (using authoryear-ibid style))
to the standard
\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}
\usepackage[style=authoryear, backend=biber]{biblatex}
\DeclareNameAlias{sortname}{family-given}
\addbibresource{biblatex-examples.bib}
\begin{document}
\cite{sigfridsson,worman,nussbaum,geer}
\printbibliography
\end{document}

The names of the authors, which determine the sorting, are much more prominent here, making it easier to navigate a longer bibliography.
The solution above naively just uses enumerate and does not expose the numbers for use in citations or elsewhere. With code similar to How to add citation number to bibliography when using bibstyle=authoryear and justification issue (I just copied the relevant code from numeric.bbx) you can let biblatex take care of the numbering, which means that is part of the entry data and can be used in citations directly.
\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}
\usepackage[style=authoryear, labelnumber, backend=biber]{biblatex}
\DeclareNameAlias{sortname}{family-given}
\DeclareFieldFormat{labelnumberwidth}{#1.}
\defbibenvironment{bibliography}
{\list
{\printtext[labelnumberwidth]{%
\printfield{labelprefix}%
\printfield{labelnumber}}}
{\setlength{\labelwidth}{\labelnumberwidth}%
\setlength{\leftmargin}{\labelwidth}%
\setlength{\labelsep}{\biblabelsep}%
\addtolength{\leftmargin}{\labelsep}%
\setlength{\itemsep}{\bibitemsep}%
\setlength{\parsep}{\bibparsep}}%
\renewcommand*{\makelabel}[1]{\hss##1}}
{\endlist}
{\item}
\addbibresource{biblatex-examples.bib}
\begin{document}
\cite{sigfridsson,worman,nussbaum,geer}
\printbibliography
\end{document}

Conversely, it is possible to combine a full numeric citation style with the layout of the author-year bibliography. See Combining style numeric with style authoryear in BibLaTeX.