Part 2: here is my report on the topic --
I am 36, financially well-off but not rich, and live in India. My most important reason for mixing and matching home theatre speakers is that I have a lot of different speakers and amplifiers that i collected or were gifted to me over the last 12 years (most of them ordinary commercial brands and not 'audiophile components') and a few vintage speakers from my late grandfather who also loved music. I listen to Indian classical and semi-classical music, jazz instrumental and also classical chamber music without orchestral support, mainly featuring cello and/or double bass.
Since I don't trade off components, I have a relatively inexpensive mix'n'match audio system (mainly for 2 channel music but also two for HDTV) in almost every room and each system rather has a unique sound.
I have not really gone by brand names, but much more by the basic principles of audio, with an 'ear open' always for the character and quality of the 'mixed' output sound.
I like to have a subwoofer, a good pair of left and right front speaker combinations, and an experimental but practically effective centre configuration to play the two_channel input in a sonically dynamic manner, giving equal importance to bass and audio clarity, with the aim of reproducing a very realistic audio output.
I prefer to use powerful woofers for bass, good quality full-range speakers for midrange and separate smaller speakers and tweeters to represent the higher frequencies. Since components are from varied sources, it takes a bit of trial to get a good sound.
In my experience, mixing and matching audio components is indeed very experimental, but if you know what sound you want to achieve, you can probably make use of each component in an interesting manner. Of course there is no jury of experts waiting to evaluate the results, but we can learn to assess the sound critically and make appropriate adjustments to get a better outcome.
Above all, mixing is fun and inexpensive. But if we want an accomplished home theatre setup within a reasonable budget, without mixing components, then we can begin to save up for it and, at a considerable (but very worthwhile) expense, purchase as a proper set, or assemble from scratch, a single-origin, pre-matched, pedigreed and excellent audio system.
(Thanks to all for previous inputs to original post, and for reading this reply.)