Block is genuinely viable, but not for the reason you think. The damage reflect perks are honestly underwhelming - they proc inconsistently and don't scale well. What actually makes sword-and-board work is that you're freeing up your damage output in ways two-handed can't.
One-handed damage per hit is lower, yeah, but your attack speed is way faster, and you can pump Smithing / Enchanting to ridiculous levels on a sword without feeling like you're wasting points. Pair that with the perks that boost your damage after blocking (the riposte one, if I'm remembering the name right), and you're actually outputting solid DPS between blocks. You won't hit a wall at level 25-30 if you're upgrading your gear - that's the real bottleneck, not the perks.
Block scaling is fine if you actually invest in it. Rush the early defensive stuff, but don't sleep on the perks that let you bash without depleting your stamina pool - that's where the playstyle gets fun. Shield bashing staggered enemies opens up follow-up damage windows that two-handed just doesn't get.
If you're on PC and want to experiment without committing, Ordinator completely rebalances the block tree and makes some of those reflect ideas actually worth taking. But vanilla? You'll be fine. Just don't expect block to carry your damage - your sword does that.