Very nice! I actually found a mint 8800b in the rafters here at work during a cleanout. Took it home and added it to my collection. It was used as a PLC to control a machine with custom I/O cards and ROM around the very late 70's.
The Z80's nice, but I always thought of the 6809 as the Chrysler Cordoba of 8 bit microprocessors, with soft Corinthian Leather upholstery and a luxurious automatic multiply instruction.
That's a bit like asking what did carpenters did with hammers and hand-saws in this age of CAD/CAM. :)
I assure you the Altairs were quite useful. Mostly, owners enjoyed the luxury of working on their very own computer, rather than a time-share machine's account from the corporation or university.
It's difficult to communicate how this felt, in this age of ubiquitous computing. A machine that one could reboot whenever you wanted. Tinker. Explore. They wrote games. Controlled hardware. Learned what made a computer tick. Connect a modem and talk to others. Sure, it was primitive, but at the time it felt as cutting-edge as space travel.
If I recall correctly, the Altair ran CP/M, and could run the early Zork infocom text adventure series.
I guess the basic model was so lacking in features that I found it hard to understand how people would make use of it. So it's more like asking how people actually used old steam cars after watching a video of Jay Leno spending hours prepping his and learning they could only drive 15 miles between fill-ups.
I did some research after posting that and realized that you could get teletype terminals for them. This makes it much easier to see what people did. I originally thought that most people punched op-codes into that front panel, which seems like an awful lot of work for not much reward.
All of my college peeps learned BASIC* while running the interpreter. We learned to fingerbone in the seq. to load from the tape, after the tape loaded I don't recall, but we then could get an OK prompt maybe from the BASIC interpreter. We used TeleType terminals w/paper rolls to print, with a tape reader. In parallel we learned Motorola MC6800 mach language on the new Heathkit trainers; our final task was to interface a speaker and play "Anchors Away" as my prof was an ex Navy instructor. *We learned BASIC, but by applying it to data and practical problems IIRC like physics of projectile motion, electrical like resistors, simple databases. Was a Pop Electronics reader from 1970 or so.