Disposable mowers, whatever works; there's no guarantee commercial equipment is going to last x no. of years either. Well yes there is quite literally a guarantee, but you know what I mean. Something goes wrong, & warrantees don't always pan out as expected, exclusions, accusations of wrong gas, user error, dealer stauling, excuses, waiting on parts etc.
Ultimately OP is paying a premium for the convenience of having new machines every year, without worrying about too much maintenance. Whether that's worth it may vary per individual needs, but it sounds like op is happy. Idk about no blade sharpening for 600hrs though, & assuming they keep lasting.
interesting, thanks for sharIng.