[chaosprime]

What you're saying about add-on layers is entirely on-point. However, telnet does not work perfectly. Telnet is broken. Why? Because character mode is part of the specification. Some vanishingly small percentage of running code actually implements the specification for it. A much larger percentage of running code implements a transitional out-of-spec hack for it from back in the day, and generally does a crap job of even that. What I found with SecureCRT was that it does support character mode, using the out-of-spec hack, if you engage character mode at the beginning of the session, after which you can never switch back to line mode. (This is to say, VanDyke's developers already had all the code they needed, they just needed to switch it on or off under any definable conditions, in-spec or out-of-spec, and couldn't be bothered.)