Good question, Odium! Neither western sidereal, western tropical, or Vedic/Hindu (sideral) astrology have really been based upon the constellations for many centuries: probably for a few millenia, although I am unsure of my history of astrology. Basically all of these systems are based upon dividing the heavens into 12 pie-sections based upon signs and/or houses. In western astrology, the sign sectors are of equal size, but you could get unequal pie sections (with so-called unequal house methods) or equal pie sections (based upon the whole-sign house system or equal house system.) But none of these is based upon the actual constellations as they pass through the ecliptic. And the problem is somewhat complicated by the fact that some of the constellations spatially overlap from an earth-centred perspective, or else they leave "gaps" in the heavens with no zodiacal constellations on portions of the ecliptic.
Vedic/sidereal astrology do account for the precession of the equinoxes, and thus are somewhat closer to the constellations for which 30-degree signs were named. But the overlap isn't 100% because most constellations are either larger or smaller than 30 degrees along the ecliptic. Tropical western astrology's sign placements are way removed from the constellations today, but we do get 0 degrees Aries at the spring equinox, 0 degrees Cancer at the summer solstice, &c. I. e., the tropical zodiac stays true to solar seasons as they are experienced in temperate climates of the northern hemisphere.
Very few astrologers today seem to look at actual constellations, which should include Ophichus--and maybe even turf out Aries, which hardly touches the ecliptic.
If you can purchase a copy of it via an Internet book seller you might be interested in John Lash,
Quest for the Zodiac, and his "star-based" approach, which includes Ophiuchus. Or this thread on another astro-forum which contains some links: the forum of
www.astro.com . [Sorry, I just double-checked the thread link but it showed only showed the main boards, but this was under my name as OP on p. 9 of "other branches of astrology as of today: this number will change, of course.]
As you learn more astrology, you can determine which system just works best for you. In western tropical astrology, my chart is mostly air and fire, which rings true to my experience, even though the sideral or 'star based" approaches appeal to me more as astrological systems.