High fee times are when lightning is most needed/wanted, but also when it’s the most painful and costly to have something screw up. Good connectivity for reliably sending meaningfully sized payments without them failing isn’t cheap. You lock up a lot of capital in a hot wallet to maintain those channels with adequate liquidity, and a lot of time monitoring and backing up channel states. Lightning is amazing but running a full always-on node just to receive zaps is overkill and puts a lot more money at risk than what you might lose if a custodial wallet rugs.