Most modern databases aren’t good at handling table with many columns (on the order of a few hundred). The point of the Block Group is for handling cases like yours that would have too many datapoints to efficiently store them into columns. You can create a new column that is the name or number of the tag and then use that in your where clause to filter out the results.
If you really want each data point to be a new column, then you have to use the standard group. Beware using this method for more than 100 columns though, queries against it become very memory intensive.