You can, of course, achieve the same thing using a line chart. You have to multiply it for each of the categories (you can do that in Power BI using small multiples). However, if you have many categories, then a small multiple might now show a nice view. that is why Sparkline can be helpful.
Sparklines are normally with minimal information. Their X-axis is a trend based on date (or something similar), but the axis is hidden because of minimal space. You can use the sparkline to understand the trend, the highest, the lowest, the starting and the ending point, etc. Because of their minimal nature, Sparklines are not used for a very detailed analysis. Instead, they are used to understand the trend of different categories over time in a high-level view.
Click through to see how you can add a sparkline to a table or matrix.