If you're set up to replace the hydrogen as it escapes then your lifting gas is a fuel you have to buy for every flight in addition to the fuel for your engines and now you're paying an energy tax to haul fuel and lifting gas in addition to cargo. This makes the entire setup an even worse competitor against planes, trucks, and ships.

Many of the ideas we all come up with for airships technically will work and the fact that we keep thinking of these things over and over again through the years speaks to how fascinating the concept of an airship is; however, we've never had a problem making an airship that works. That's the easy part. Making one that anyone would want to use for everyday transport is the hard problem.

A leaky bag of hydrogen in bad weather. What could possibly go wrong?