The sealant and O-rings were meant to keep the hot gasses inside. Simply making a joint slightly wiggly will not keep hot gasses inside. The hot gasses did not stay inside. The sealant and O-rings did not succeed in keeping the hot gasses inside (evidence: Challenger). They were not adequate
> The sealant and O-rings did not succeed in keeping the hot gasses inside (evidence: Challenger). They were not adequate
No. The whole assembly --joint, sealant and O-rings, -- failed.
"They were not adequate" - yet, after the redesign, they kept those same O-rings and declared that boosters are safe to fly, in manifest contradiction to your assertion. So your reasoning is clearly flawed.