Then that's your problem, not the maintenance. With no indexes at all, no clustered index, the table is a heap. Firstly index rebuilds won't touch heaps, second deletes don't deallocate empty pages unless the delete runs with a table lock. Hence you have a table that's mostly full of empty space.
I've seen an empty table (0 rows) that when read processed 600MB of pages.
At minimum put a clustered index on that, and every other table in your DB. Consider other indexes too.
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: Discussions on DB performance with occasional diversions into recoverability
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