The rest of the series, however, amply demonstrates that you can solve the problem of the Reapers by shooting them a lot. Seriously, the combined fleet almost immediately starts inflicting damage on the Reapers, blowing space tentacles off one with almost their opening volley.
Indeed. By setting off the Crucible. They made it absolutely clear that there was no other way of defeating them without it and they weren't sure what it did. I was particularly surprised that it wasn't actually the magic 'make everything ok' option Bioware had provided for every other plot-point, but there you go.
The plot has revolved around saving everyone from certain death at the space-tentacles of the Reapers.
The solutions provided are rather like curing a cancer patient by chopping his head off.